From fec8c688994d92e80641f8abc213e867bb6b4df8 Mon Sep 17 00:00:00 2001
From: zoziha13 <1325686572@qq.com>
Date: Sat, 26 Jun 2021 02:37:17 +0800
Subject: [PATCH 01/14] add: 1. src/stdlib_io_disp.fypp 2.
 src/tests/string/test_io_disp.f90 3. stdlib_io.fypp%disp interface modify: 1.
 doc/spec/stdlib_io.md%disp(doc) 2. src/Makefile.manual%disp(make) 3.
 src/tests/string/Makefile.manual%disp(make) 4. src/CMakelists.txt%disp(cmake)
 5. src/CMakelists.txt%disp(cmake) note: make test passed. cmake test passed

---
 doc/specs/stdlib_io.md        |  95 ++++++++++++++++++++++++++
 src/CMakeLists.txt            |   1 +
 src/Makefile.manual           |   9 ++-
 src/stdlib_io.fypp            |  31 ++++++++-
 src/stdlib_io_disp.fypp       | 125 ++++++++++++++++++++++++++++++++++
 src/tests/io/CMakeLists.txt   |   1 +
 src/tests/io/Makefile.manual  |   3 +-
 src/tests/io/test_io_disp.f90 |  24 +++++++
 8 files changed, 284 insertions(+), 5 deletions(-)
 create mode 100644 src/stdlib_io_disp.fypp
 create mode 100644 src/tests/io/test_io_disp.f90

diff --git a/doc/specs/stdlib_io.md b/doc/specs/stdlib_io.md
index 40cb2b426..3f44f6476 100644
--- a/doc/specs/stdlib_io.md
+++ b/doc/specs/stdlib_io.md
@@ -131,3 +131,98 @@ program demo_savetxt
     call savetxt('example.dat', x) 
 end program demo_savetxt
 ```
+
+## `disp` - quickly display your data to the screen (or the default output location)
+
+### Status
+
+Experimental
+
+### Description
+Quickly display strings, scalars and low-dimensional arrays to the screen (or the default output location).
+
+### Syntax
+
+For 3D arrays:
+`call [[stdlib_io(module):disp(interface)]](value, dim [, string])`  
+For null:
+`call [[stdlib_io(module):disp(interface)]]()`  
+For others:
+`call [[stdlib_io(module):disp(interface)]](value [, string])`
+
+### Arguments
+
+`value`: Shall be any type of scalar or (<= 3)D `array`.
+
+`dim`: Shall be a scalar of type `integer` with a value: 1, 2 or 3.
+
+`string`: Shall be a scalar of type `character` with any length(Usually used to mark data information).
+
+### Output
+
+The result is to print your data `value` and comments `string` on the screen (or the default output location).
+
+### Example
+
+```fortran
+program demo_io_disp
+    use, non_intrinsic :: stdlib_io, only: disp
+    implicit none
+    real :: r(2, 3)
+    complex :: c(2, 3), c_3d(2, 3, 2)
+    integer :: i(2, 3)
+    logical :: l(2, 3)
+
+    r = 1.; c = 1.; c_3d = 2.; i = 1; l = .true.
+    r(1, 1) = (1.e-11, 1.0e-4)
+    c(2, 2) = 10.e5
+    c_3d(1,3,1) = (1000, 0.001)
+        call disp('string', 'disp(string):')
+        call disp('It is a note.')
+        call disp()
+
+        call disp(r, 'disp(r):')
+        call disp(c, 'disp(c):')
+        call disp(i, 'disp(i):')
+        call disp(l, 'disp(l):')
+
+        call disp(c_3d, 3, 'disp(c_3d, 3):')
+        call disp(c_3d, 2, 'disp(c_3d, 2):')
+end program demo_io_disp
+```
+**Result:**
+```fortran
+ disp(string):
+ string
+ It is a note.
+
+ disp(r):
+ 0.1000E-10   1.000       1.000
+  1.000       1.000       1.000
+ disp(c):
+          (1.000,0.000)           (1.000,0.000)           (1.000,0.000)
+          (1.000,0.000)      (0.1000E+07,0.000)           (1.000,0.000)
+ disp(i):
+          1           1           1
+          1           1           1
+ disp(l):
+          T           T           T
+          T           T           T
+ disp(c_3d, 3):
+ Slice (:,:,1):
+          (2.000,0.000)           (2.000,0.000)      (1000.,0.1000E-02)
+          (2.000,0.000)           (2.000,0.000)           (2.000,0.000)
+ Slice (:,:,2):
+          (2.000,0.000)           (2.000,0.000)           (2.000,0.000)
+          (2.000,0.000)           (2.000,0.000)           (2.000,0.000)
+ disp(c_3d, 2):
+ Slice (:,1,:):
+          (2.000,0.000)           (2.000,0.000)
+          (2.000,0.000)           (2.000,0.000)
+ Slice (:,2,:):
+          (2.000,0.000)           (2.000,0.000)
+          (2.000,0.000)           (2.000,0.000)
+ Slice (:,3,:):
+     (1000.,0.1000E-02)           (2.000,0.000)
+          (2.000,0.000)           (2.000,0.000)
+```
diff --git a/src/CMakeLists.txt b/src/CMakeLists.txt
index 88bf89c56..77aed09b1 100644
--- a/src/CMakeLists.txt
+++ b/src/CMakeLists.txt
@@ -7,6 +7,7 @@ set(fppFiles
     stdlib_bitsets_64.fypp
     stdlib_bitsets_large.fypp
     stdlib_io.fypp
+    stdlib_io_disp.fypp
     stdlib_linalg.fypp
     stdlib_linalg_diag.fypp
     stdlib_optval.fypp
diff --git a/src/Makefile.manual b/src/Makefile.manual
index c10eddccb..1a1d40811 100644
--- a/src/Makefile.manual
+++ b/src/Makefile.manual
@@ -27,7 +27,8 @@ SRCFYPP =\
         stdlib_stats_distribution_PRNG.fypp \
         stdlib_string_type.fypp \
         stdlib_strings.fypp \
-        stdlib_strings_format_string.fypp
+        stdlib_strings_format_string.fypp \
+        stdlib_io_disp.fypp
 
 SRC = f18estop.f90 \
       stdlib_error.f90 \
@@ -69,7 +70,8 @@ stdlib_error.o: stdlib_optval.o
 stdlib_io.o: \
 	stdlib_error.o \
 	stdlib_optval.o \
-	stdlib_kinds.o
+	stdlib_kinds.o \
+    stdlib_ascii.o
 stdlib_linalg.o: \
 	stdlib_kinds.o
 stdlib_linalg_diag.o: \
@@ -134,3 +136,6 @@ stdlib_strings.o: stdlib_ascii.o \
     stdlib_kinds.o
 stdlib_math.o: stdlib_kinds.o
 stdlib_strings_format_string.o: stdlib_strings.o
+stdlib_io_disp.o: stdlib_error.o \
+    stdlib_strings.o \
+    stdlib_io.o
diff --git a/src/stdlib_io.fypp b/src/stdlib_io.fypp
index dcacaa644..dd6cc3d85 100644
--- a/src/stdlib_io.fypp
+++ b/src/stdlib_io.fypp
@@ -7,18 +7,45 @@ module stdlib_io
   !! ([Specification](../page/specs/stdlib_io.html))
 
   use stdlib_kinds, only: sp, dp, qp, &
-      int8, int16, int32, int64
+      int8, int16, int32, int64, lk, c_bool
   use stdlib_error, only: error_stop
   use stdlib_optval, only: optval
   use stdlib_ascii, only: is_blank
   implicit none
   private
   ! Public API
-  public :: loadtxt, savetxt, open
+  public :: loadtxt, savetxt, open, disp
 
   ! Private API that is exposed so that we can test it in tests
   public :: parse_mode
 
+  interface disp
+    !!
+    #:set DISP_KINDS_TYPES = REAL_KINDS_TYPES + INT_KINDS_TYPES &
+        & + CMPLX_KINDS_TYPES + LOG_KINDS_TYPES
+    #:set DISP_RANKS = range(0, 4)
+    #:for kind, type in DISP_KINDS_TYPES
+    #:for rank in DISP_RANKS
+    #:if rank != 3
+    impure module subroutine disp_${rank}$_${type[0]}$${kind}$(val, string)
+        ${type}$, intent(in) :: val${ranksuffix(rank)}$
+        character(len=*), intent(in), optional :: string
+    end subroutine disp_${rank}$_${type[0]}$${kind}$
+    #:else
+    impure module subroutine disp_${rank}$_${type[0]}$${kind}$(val, dim, string)
+        ${type}$, intent(in) :: val${ranksuffix(rank)}$
+        integer, intent(in) :: dim
+        character(len=*), intent(in), optional :: string
+    end subroutine disp_${rank}$_${type[0]}$${kind}$
+    #:endif
+    #:endfor
+    #:endfor
+    impure module subroutine disp_str(val, string)
+        character(len=*), intent(in), optional :: val
+        character(len=*), intent(in), optional :: string
+    end subroutine disp_str
+  end interface disp
+
   interface loadtxt
     !! version: experimental
     !!
diff --git a/src/stdlib_io_disp.fypp b/src/stdlib_io_disp.fypp
new file mode 100644
index 000000000..66d9694cb
--- /dev/null
+++ b/src/stdlib_io_disp.fypp
@@ -0,0 +1,125 @@
+#:include "common.fypp"
+#:set RIL_KINDS_TYPES = REAL_KINDS_TYPES + INT_KINDS_TYPES + LOG_KINDS_TYPES
+
+submodule (stdlib_io) stdlib_io_disp
+
+    use, non_intrinsic :: stdlib_strings, only: format_string
+    implicit none
+    character(len=*), parameter :: fmt_r = '(*(g11.4, 1x))'
+    character(len=*), parameter :: fmt_c = '(*(g23.4, 1x))'
+    
+contains
+    
+    #:for kind, type in RIL_KINDS_TYPES
+    module procedure disp_0_${type[0]}$${kind}$
+        if(present(string)) print *, trim(string)
+        print fmt_r, val
+    end procedure disp_0_${type[0]}$${kind}$
+
+    module procedure disp_1_${type[0]}$${kind}$
+        integer :: i, m
+        m = size(val)
+        if(present(string)) print *, trim(string)
+        print fmt_r, (val(i), i=1,m)
+    end procedure disp_1_${type[0]}$${kind}$
+
+    module procedure disp_2_${type[0]}$${kind}$
+        integer :: i, j, m, n
+        m = size(val, 1)
+        n = size(val, 2)
+        if(present(string)) print *, trim(string)
+        do i = 1, m
+            print fmt_r, (val(i,j), j=1, n)
+        end do
+    end procedure disp_2_${type[0]}$${kind}$
+
+    module procedure disp_3_${type[0]}$${kind}$
+        integer :: i, dim1, dim2, dim3
+        dim1 = size(val, 1)
+        dim2 = size(val, 2)
+        dim3 = size(val, 3)
+        if(present(string)) print *, trim(string)
+        if(dim == 1) then
+            do i = 1, dim1
+                print *, 'Slice ('//format_string(i)//',:,:):'
+                call disp_2_${type[0]}$${kind}$(val(i, :, :))
+            end do
+        elseif(dim == 2) then
+            do i = 1, dim2
+                print *, 'Slice (:,'//format_string(i)//',:):'
+                call disp_2_${type[0]}$${kind}$(val(:, i, :))
+            end do
+        elseif (dim == 3) then
+            do i = 1, dim3
+                print *, 'Slice (:,:,'//format_string(i)//'):'
+                call disp_2_${type[0]}$${kind}$(val(:, :, i))
+            end do
+        else
+            call error_stop('Error(disp): wrong dimension')
+        end if
+    end procedure disp_3_${type[0]}$${kind}$
+    #:endfor
+
+    #:for kind, type in CMPLX_KINDS_TYPES
+    module procedure disp_0_${type[0]}$${kind}$
+        if(present(string)) print *, trim(string)
+        print fmt_c, format_string(cmplx(real(val), &
+                                         aimag(val)), '(g11,4)')
+    end procedure disp_0_${type[0]}$${kind}$
+
+    module procedure disp_1_${type[0]}$${kind}$
+        integer :: i, m
+        m = size(val)
+        if(present(string)) print *, trim(string)
+        print fmt_c, (format_string(cmplx(real(val(i)), &
+                        aimag(val(i))), '(g11.4)'), i=1, m)
+    end procedure disp_1_${type[0]}$${kind}$
+
+    module procedure disp_2_${type[0]}$${kind}$
+        integer :: i, j, m, n
+        m = size(val, 1)
+        n = size(val, 2)
+        if(present(string)) print *, trim(string)
+        do i = 1, m
+            print fmt_c, (format_string(cmplx(real(val(i, j)), &
+                            aimag(val(i, j))), '(g11.4)'), j=1, n)
+        end do
+    end procedure disp_2_${type[0]}$${kind}$
+
+    module procedure disp_3_${type[0]}$${kind}$
+        integer :: i, dim1, dim2, dim3
+        dim1 = size(val, 1)
+        dim2 = size(val, 2)
+        dim3 = size(val, 3)
+        if(present(string)) print *, trim(string)
+        if(dim == 1) then
+            do i = 1, dim1
+                print *, 'Slice ('//format_string(i)//',:,:):'
+                call disp_2_${type[0]}$${kind}$(val(i, :, :))
+            end do
+        elseif(dim == 2) then
+            do i = 1, dim2
+                print *, 'Slice (:,'//format_string(i)//',:):'
+                call disp_2_${type[0]}$${kind}$(val(:, i, :))
+            end do
+        elseif (dim == 3) then
+            do i = 1, dim3
+                print *, 'Slice (:,:,'//format_string(i)//'):'
+                call disp_2_${type[0]}$${kind}$(val(:, :, i))
+            end do
+        else
+            call error_stop('Error(disp): wrong dimension')
+        end if
+    end procedure disp_3_${type[0]}$${kind}$
+    #:endfor
+
+    module procedure disp_str
+        if(present(string)) print *, trim(string)
+        if(present(val)) then
+            print *, trim(val)
+        else
+            print *, ''
+        end if
+    end procedure disp_str
+
+end submodule stdlib_io_disp
\ No newline at end of file
diff --git a/src/tests/io/CMakeLists.txt b/src/tests/io/CMakeLists.txt
index 68388a5e5..97c97757b 100644
--- a/src/tests/io/CMakeLists.txt
+++ b/src/tests/io/CMakeLists.txt
@@ -8,3 +8,4 @@ set_tests_properties(savetxt_qp PROPERTIES LABELS quadruple_precision)
 
 ADDTEST(open)
 ADDTEST(parse_mode)
+ADDTEST(io_disp)
diff --git a/src/tests/io/Makefile.manual b/src/tests/io/Makefile.manual
index 3bbce9db7..3ec21eacb 100644
--- a/src/tests/io/Makefile.manual
+++ b/src/tests/io/Makefile.manual
@@ -3,7 +3,8 @@ PROGS_SRC = test_loadtxt.f90 \
 			test_loadtxt_qp.f90 \
 			test_savetxt_qp.f90 \
 			test_parse_mode.f90 \
-			test_open.f90
+			test_open.f90 \
+            test_io_disp.f90
 
 CLEAN_FILES = tmp.dat tmp_qp.dat io_open.dat io_open.stream
 
diff --git a/src/tests/io/test_io_disp.f90 b/src/tests/io/test_io_disp.f90
new file mode 100644
index 000000000..bb6abc362
--- /dev/null
+++ b/src/tests/io/test_io_disp.f90
@@ -0,0 +1,24 @@
+program test_io_disp
+    use, non_intrinsic :: stdlib_io, only: disp
+    implicit none
+    real :: r(2, 3)
+    complex :: c(2, 3), c_3d(2, 3, 2)
+    integer :: i(2, 3)
+    logical :: l(2, 3)
+
+    r = 1.; c = 1.; c_3d = 2.; i = 1; l = .true.
+    r(1, 1) = (1.e-11, 1.0e-4)
+    c(2, 2) = 10.e5
+    c_3d(1,3,1) = (1000, 0.001)
+        call disp('string', 'disp(string):')
+        call disp('It is a note.')
+        call disp()
+
+        call disp(r, 'disp(r):')
+        call disp(c, 'disp(c):')
+        call disp(i, 'disp(i):')
+        call disp(l, 'disp(l):')
+
+        call disp(c_3d, 3, 'disp(c_3d, 3):')
+        call disp(c_3d, 2, 'disp(c_3d, 2):')
+end program test_io_disp
\ No newline at end of file

From df88c550cd26c474e885ae2810e5ec8e31554ef9 Mon Sep 17 00:00:00 2001
From: zoziha13 <1325686572@qq.com>
Date: Mon, 28 Jun 2021 00:18:50 +0800
Subject: [PATCH 02/14] Fix stdlib_io_disp routines. --- - stdlib_io.fypp 1.
 add disp interface comments 2. remove `impure` label - stdlib_io_disp.fypp 1.
 remove `non_intrinsic` label 2. update some `format_string` to `to_string` 3.
 update `fmt_r` & `fmt_c` 4. add some routine comments 5. update the writing
 of some statements - update test_io_disp.f90 - notes 1. make passed 2. cmake
 passed

---
 src/stdlib_io.fypp            |  9 ++++---
 src/stdlib_io_disp.fypp       | 46 +++++++++++++++++++----------------
 src/tests/io/test_io_disp.f90 |  8 +++---
 3 files changed, 36 insertions(+), 27 deletions(-)

diff --git a/src/stdlib_io.fypp b/src/stdlib_io.fypp
index dd6cc3d85..1f40dbd0b 100644
--- a/src/stdlib_io.fypp
+++ b/src/stdlib_io.fypp
@@ -20,19 +20,22 @@ module stdlib_io
   public :: parse_mode
 
   interface disp
+    !! version: experimental
     !!
+    !! Quickly display strings, scalars and low-dimensional arrays to the default output_unit
+    !! ([Specification](../page/specs/stdlib_io.html#description))
     #:set DISP_KINDS_TYPES = REAL_KINDS_TYPES + INT_KINDS_TYPES &
         & + CMPLX_KINDS_TYPES + LOG_KINDS_TYPES
     #:set DISP_RANKS = range(0, 4)
     #:for kind, type in DISP_KINDS_TYPES
     #:for rank in DISP_RANKS
     #:if rank != 3
-    impure module subroutine disp_${rank}$_${type[0]}$${kind}$(val, string)
+    module subroutine disp_${rank}$_${type[0]}$${kind}$(val, string)
         ${type}$, intent(in) :: val${ranksuffix(rank)}$
         character(len=*), intent(in), optional :: string
     end subroutine disp_${rank}$_${type[0]}$${kind}$
     #:else
-    impure module subroutine disp_${rank}$_${type[0]}$${kind}$(val, dim, string)
+    module subroutine disp_${rank}$_${type[0]}$${kind}$(val, dim, string)
         ${type}$, intent(in) :: val${ranksuffix(rank)}$
         integer, intent(in) :: dim
         character(len=*), intent(in), optional :: string
@@ -40,7 +43,7 @@ module stdlib_io
     #:endif
     #:endfor
     #:endfor
-    impure module subroutine disp_str(val, string)
+    module subroutine disp_str(val, string)
         character(len=*), intent(in), optional :: val
         character(len=*), intent(in), optional :: string
     end subroutine disp_str
diff --git a/src/stdlib_io_disp.fypp b/src/stdlib_io_disp.fypp
index 66d9694cb..aa4b8e96d 100644
--- a/src/stdlib_io_disp.fypp
+++ b/src/stdlib_io_disp.fypp
@@ -3,37 +3,39 @@
 
 submodule (stdlib_io) stdlib_io_disp
 
-    use, non_intrinsic :: stdlib_strings, only: format_string
+    use stdlib_ascii, only: to_string
+    use stdlib_strings, only: format_string
     implicit none
-    character(len=*), parameter :: fmt_r = '(*(g11.4, 1x))'
-    character(len=*), parameter :: fmt_c = '(*(g23.4, 1x))'
+    character(len=*), parameter :: fmt_r = '(*(g12.4, 1x))'
+    character(len=*), parameter :: fmt_c = '(*(g25.0, 1x))'
     
 contains
     
     #:for kind, type in RIL_KINDS_TYPES
     module procedure disp_0_${type[0]}$${kind}$
+        !! Disp ${type}$ variable to default output_unit
         if(present(string)) print *, trim(string)
         print fmt_r, val
     end procedure disp_0_${type[0]}$${kind}$
 
     module procedure disp_1_${type[0]}$${kind}$
-        integer :: i, m
-        m = size(val)
+        !! Disp ${type}$ vector variable to default output_unit
         if(present(string)) print *, trim(string)
-        print fmt_r, (val(i), i=1,m)
+        print fmt_r, val(:)
     end procedure disp_1_${type[0]}$${kind}$
 
     module procedure disp_2_${type[0]}$${kind}$
-        integer :: i, j, m, n
+        !! Disp ${type}$ 2D array variable to default output_unit
+        integer :: i, m
         m = size(val, 1)
-        n = size(val, 2)
         if(present(string)) print *, trim(string)
         do i = 1, m
-            print fmt_r, (val(i,j), j=1, n)
+            print fmt_r, val(i,:)
         end do
     end procedure disp_2_${type[0]}$${kind}$
 
     module procedure disp_3_${type[0]}$${kind}$
+        !! Disp ${type}$ 3D array variable to default output_unit
         integer :: i, dim1, dim2, dim3
         dim1 = size(val, 1)
         dim2 = size(val, 2)
@@ -41,17 +43,17 @@ contains
         if(present(string)) print *, trim(string)
         if(dim == 1) then
             do i = 1, dim1
-                print *, 'Slice ('//format_string(i)//',:,:):'
+                print *, 'Slice ('//to_string(i)//',:,:):'
                 call disp_2_${type[0]}$${kind}$(val(i, :, :))
             end do
         elseif(dim == 2) then
             do i = 1, dim2
-                print *, 'Slice (:,'//format_string(i)//',:):'
+                print *, 'Slice (:,'//to_string(i)//',:):'
                 call disp_2_${type[0]}$${kind}$(val(:, i, :))
             end do
         elseif (dim == 3) then
             do i = 1, dim3
-                print *, 'Slice (:,:,'//format_string(i)//'):'
+                print *, 'Slice (:,:,'//to_string(i)//'):'
                 call disp_2_${type[0]}$${kind}$(val(:, :, i))
             end do
         else
@@ -62,31 +64,32 @@ contains
 
     #:for kind, type in CMPLX_KINDS_TYPES
     module procedure disp_0_${type[0]}$${kind}$
+        !! Disp ${type}$ variable to default output_unit
         if(present(string)) print *, trim(string)
-        print fmt_c, format_string(cmplx(real(val), &
-                                         aimag(val)), '(g11,4)')
+        print fmt_c, format_string(val, '(g0.4)')
     end procedure disp_0_${type[0]}$${kind}$
 
     module procedure disp_1_${type[0]}$${kind}$
+        !! Disp ${type}$ vector variable to default output_unit
         integer :: i, m
         m = size(val)
         if(present(string)) print *, trim(string)
-        print fmt_c, (format_string(cmplx(real(val(i)), &
-                        aimag(val(i))), '(g11.4)'), i=1, m)
+        print fmt_c, (format_string(val(i), '(g0.4)'), i=1, m)
     end procedure disp_1_${type[0]}$${kind}$
 
     module procedure disp_2_${type[0]}$${kind}$
+        !! Disp ${type}$ 2D array variable to default output_unit
         integer :: i, j, m, n
         m = size(val, 1)
         n = size(val, 2)
         if(present(string)) print *, trim(string)
         do i = 1, m
-            print fmt_c, (format_string(cmplx(real(val(i, j)), &
-                            aimag(val(i, j))), '(g11.4)'), j=1, n)
+            print fmt_c, (format_string(val(i, j), '(g0.4)'), j=1, n)
         end do
     end procedure disp_2_${type[0]}$${kind}$
 
     module procedure disp_3_${type[0]}$${kind}$
+        !! Disp ${type}$ 3D array variable to default output_unit
         integer :: i, dim1, dim2, dim3
         dim1 = size(val, 1)
         dim2 = size(val, 2)
@@ -94,17 +97,17 @@ contains
         if(present(string)) print *, trim(string)
         if(dim == 1) then
             do i = 1, dim1
-                print *, 'Slice ('//format_string(i)//',:,:):'
+                print *, 'Slice ('//to_string(i)//',:,:):'
                 call disp_2_${type[0]}$${kind}$(val(i, :, :))
             end do
         elseif(dim == 2) then
             do i = 1, dim2
-                print *, 'Slice (:,'//format_string(i)//',:):'
+                print *, 'Slice (:,'//to_string(i)//',:):'
                 call disp_2_${type[0]}$${kind}$(val(:, i, :))
             end do
         elseif (dim == 3) then
             do i = 1, dim3
-                print *, 'Slice (:,:,'//format_string(i)//'):'
+                print *, 'Slice (:,:,'//to_string(i)//'):'
                 call disp_2_${type[0]}$${kind}$(val(:, :, i))
             end do
         else
@@ -114,6 +117,7 @@ contains
     #:endfor
 
     module procedure disp_str
+        !! Disp character variable to default output_unit
         if(present(string)) print *, trim(string)
         if(present(val)) then
             print *, trim(val)
diff --git a/src/tests/io/test_io_disp.f90 b/src/tests/io/test_io_disp.f90
index bb6abc362..6bb7ccfec 100644
--- a/src/tests/io/test_io_disp.f90
+++ b/src/tests/io/test_io_disp.f90
@@ -1,15 +1,17 @@
 program test_io_disp
     use, non_intrinsic :: stdlib_io, only: disp
     implicit none
-    real :: r(2, 3)
+    real(8) :: r(2, 3)
     complex :: c(2, 3), c_3d(2, 3, 2)
     integer :: i(2, 3)
     logical :: l(2, 3)
 
     r = 1.; c = 1.; c_3d = 2.; i = 1; l = .true.
-    r(1, 1) = (1.e-11, 1.0e-4)
-    c(2, 2) = 10.e5
+    r(1, 1) = -1.e-11
+    r(1, 2) = -1.e10
+    c(2, 2) = (-1.e10,-1.e10)
     c_3d(1,3,1) = (1000, 0.001)
+    c_3d(1,3,2) = (1.e4, 100.)
         call disp('string', 'disp(string):')
         call disp('It is a note.')
         call disp()

From cb4cecc9cda33902227ef96ef1921dabeb87988f Mon Sep 17 00:00:00 2001
From: zoziha13 <1325686572@qq.com>
Date: Tue, 6 Jul 2021 11:18:55 +0800
Subject: [PATCH 03/14] Update `format_to_string` things; Update `disp` docs;
 Adopt `select case` block; Adopt the `fypp` inline rank writing; Rename
 `disp` input arg: val -> value.

---
 doc/specs/stdlib_io.md  | 99 +++++++++++++++++++++++------------------
 src/Makefile.manual     |  6 +--
 src/stdlib_io.fypp      | 21 +++------
 src/stdlib_io_disp.fypp | 79 ++++++++++++++++----------------
 4 files changed, 105 insertions(+), 100 deletions(-)

diff --git a/doc/specs/stdlib_io.md b/doc/specs/stdlib_io.md
index 3f44f6476..8c2c486c1 100644
--- a/doc/specs/stdlib_io.md
+++ b/doc/specs/stdlib_io.md
@@ -132,62 +132,81 @@ program demo_savetxt
 end program demo_savetxt
 ```
 
-## `disp` - quickly display your data to the screen (or the default output location)
+## `disp` - display your data to the screen (or the default `output_unit`)
 
 ### Status
 
 Experimental
 
 ### Description
-Quickly display strings, scalars and low-dimensional arrays to the screen (or the default output location).
+Display any type of scalar or `array` with up to 3 dimensions to the screen (or the default `output_unit`).  
+
+Make good use of similar to the following usage, can help you understand the data information in the `array`.
+```fortran
+call disp( A(i, j, 2, :, :) [, string] )    !! `i, j, ...` can be determined by `do` loop.
+```
+
+Generally, except for `complex` type, any other type of scalar or single element of the `array` will be printed out with a width of 12 characters and a space separator.  
+For `complex` type, scalar or single element of the `array` will be printed out with a width of 25 characters and a space separator.
 
 ### Syntax
 
-For 3D arrays:
-`call [[stdlib_io(module):disp(interface)]](value, dim [, string])`  
+General API:
+`call [[stdlib_io(module):disp(interface)]](value [, string])`
+
+Except, for 3D arrays:
+`call [[stdlib_io(module):disp(interface)]](value, dim [, string])` 
+
 For null:
 `call [[stdlib_io(module):disp(interface)]]()`  
-For others:
-`call [[stdlib_io(module):disp(interface)]](value [, string])`
 
 ### Arguments
 
-`value`: Shall be any type of scalar or (<= 3)D `array`.
+`value`: Shall be any type of scalar or `array` with up to 3 dimensions.
+    This is an `intent(in)` argument.
 
 `dim`: Shall be a scalar of type `integer` with a value: 1, 2 or 3.
+    This is an `intent(in)` argument.
 
-`string`: Shall be a scalar of type `character` with any length(Usually used to mark data information).
+`string`: Shall be a scalar of type `character` with any length (usually used to comment data information).
+    This is an `intent(in)` and `optional` argument.
 
 ### Output
 
-The result is to print your data `value` and comments `string` on the screen (or the default output location).
+The result is to print `string` and `value` on the screen (or the default `output_unit`) in this order.
 
 ### Example
 
 ```fortran
 program demo_io_disp
-    use, non_intrinsic :: stdlib_io, only: disp
+
+    use :: stdlib_io, only: disp
     implicit none
-    real :: r(2, 3)
+    real(8) :: r(2, 3)
     complex :: c(2, 3), c_3d(2, 3, 2)
     integer :: i(2, 3)
     logical :: l(2, 3)
 
     r = 1.; c = 1.; c_3d = 2.; i = 1; l = .true.
-    r(1, 1) = (1.e-11, 1.0e-4)
-    c(2, 2) = 10.e5
+    r(1, 1) = -1.e-11
+    r(1, 2) = -1.e10
+    c(2, 2) = (-1.e10,-1.e10)
     c_3d(1,3,1) = (1000, 0.001)
-        call disp('string', 'disp(string):')
-        call disp('It is a note.')
-        call disp()
+    c_3d(1,3,2) = (1.e4, 100.)
+
+    call disp('string', 'disp(string):')
+    call disp('It is a note.')
+    call disp()
+
+    call disp(r, 'disp(r):')
+    call disp(c, 'disp(c):')
+    call disp(i(1,:), 'disp(i):')
+    call disp(l(:,2), 'disp(l):')
 
-        call disp(r, 'disp(r):')
-        call disp(c, 'disp(c):')
-        call disp(i, 'disp(i):')
-        call disp(l, 'disp(l):')
+    call disp(c_3d, 3, 'disp(c_3d, 3):')
 
-        call disp(c_3d, 3, 'disp(c_3d, 3):')
-        call disp(c_3d, 2, 'disp(c_3d, 2):')
+    call disp(c_3d(1,:,:), 'disp(c_3d(1,:,:)):')
+    
 end program demo_io_disp
 ```
 **Result:**
@@ -197,32 +216,24 @@ end program demo_io_disp
  It is a note.
 
  disp(r):
- 0.1000E-10   1.000       1.000
-  1.000       1.000       1.000
+ -0.1000E-10  -0.1000E+11    1.000
+   1.000        1.000        1.000
  disp(c):
-          (1.000,0.000)           (1.000,0.000)           (1.000,0.000)
-          (1.000,0.000)      (0.1000E+07,0.000)           (1.000,0.000)
+            (1.000,0.000)             (1.000,0.000)             (1.000,0.000)
+            (1.000,0.000) (-0.1000E+11,-0.1000E+11)             (1.000,0.000)
  disp(i):
-          1           1           1
-          1           1           1
+           1            1            1
  disp(l):
-          T           T           T
-          T           T           T
+           T            T
  disp(c_3d, 3):
  Slice (:,:,1):
-          (2.000,0.000)           (2.000,0.000)      (1000.,0.1000E-02)
-          (2.000,0.000)           (2.000,0.000)           (2.000,0.000)
+            (2.000,0.000)             (2.000,0.000)         (1000.,0.1000E-2)
+            (2.000,0.000)             (2.000,0.000)             (2.000,0.000)
  Slice (:,:,2):
-          (2.000,0.000)           (2.000,0.000)           (2.000,0.000)
-          (2.000,0.000)           (2.000,0.000)           (2.000,0.000)
- disp(c_3d, 2):
- Slice (:,1,:):
-          (2.000,0.000)           (2.000,0.000)
-          (2.000,0.000)           (2.000,0.000)
- Slice (:,2,:):
-          (2.000,0.000)           (2.000,0.000)
-          (2.000,0.000)           (2.000,0.000)
- Slice (:,3,:):
-     (1000.,0.1000E-02)           (2.000,0.000)
-          (2.000,0.000)           (2.000,0.000)
+            (2.000,0.000)             (2.000,0.000)         (0.1000E+5,100.0)
+            (2.000,0.000)             (2.000,0.000)             (2.000,0.000)
+ disp(c_3d(1,:,:)):
+            (2.000,0.000)             (2.000,0.000)
+            (2.000,0.000)             (2.000,0.000)
+        (1000.,0.1000E-2)         (0.1000E+5,100.0)
 ```
diff --git a/src/Makefile.manual b/src/Makefile.manual
index d22ef1f06..52836fa7a 100644
--- a/src/Makefile.manual
+++ b/src/Makefile.manual
@@ -28,7 +28,7 @@ SRCFYPP =\
         stdlib_stats_distribution_PRNG.fypp \
         stdlib_string_type.fypp \
         stdlib_strings.fypp \
-        stdlib_strings_format_to_string.fypp \
+        stdlib_string_format_to_string.fypp \
         stdlib_io_disp.fypp
 
 SRC = f18estop.f90 \
@@ -136,13 +136,13 @@ stdlib_stats_var.o: \
 	stdlib_kinds.o \
 	stdlib_stats.o
 stdlib_stats_distribution_PRNG.o: \
-        stdlib_kinds.o \
+    stdlib_kinds.o \
 	stdlib_error.o
 stdlib_string_type.o: stdlib_ascii.o \
     stdlib_kinds.o
 stdlib_strings.o: stdlib_ascii.o \
     stdlib_string_type.o \
-	stdlib_optval.o \
+    stdlib_optval.o \
     stdlib_kinds.o
 stdlib_math.o: stdlib_kinds.o
 stdlib_string_format_to_string.o: stdlib_strings.o
diff --git a/src/stdlib_io.fypp b/src/stdlib_io.fypp
index 1f40dbd0b..002b7b021 100644
--- a/src/stdlib_io.fypp
+++ b/src/stdlib_io.fypp
@@ -22,29 +22,22 @@ module stdlib_io
   interface disp
     !! version: experimental
     !!
-    !! Quickly display strings, scalars and low-dimensional arrays to the default output_unit
-    !! ([Specification](../page/specs/stdlib_io.html#description))
+    !! Display any type of scalar and `array` with up to 3 dimensions to the default `output_unit`
+    !! ([Specification](../page/specs/stdlib_io.html#description_4))
     #:set DISP_KINDS_TYPES = REAL_KINDS_TYPES + INT_KINDS_TYPES &
         & + CMPLX_KINDS_TYPES + LOG_KINDS_TYPES
     #:set DISP_RANKS = range(0, 4)
     #:for kind, type in DISP_KINDS_TYPES
     #:for rank in DISP_RANKS
-    #:if rank != 3
-    module subroutine disp_${rank}$_${type[0]}$${kind}$(val, string)
-        ${type}$, intent(in) :: val${ranksuffix(rank)}$
-        character(len=*), intent(in), optional :: string
-    end subroutine disp_${rank}$_${type[0]}$${kind}$
-    #:else
-    module subroutine disp_${rank}$_${type[0]}$${kind}$(val, dim, string)
-        ${type}$, intent(in) :: val${ranksuffix(rank)}$
-        integer, intent(in) :: dim
+    module subroutine disp_${rank}$_${type[0]}$${kind}$(value, #{if rank == 3}#dim, #{endif}#string)
+        ${type}$, intent(in) :: value${ranksuffix(rank)}$
+        #{if rank == 3}#integer, intent(in) :: dim#{endif}#
         character(len=*), intent(in), optional :: string
     end subroutine disp_${rank}$_${type[0]}$${kind}$
-    #:endif
     #:endfor
     #:endfor
-    module subroutine disp_str(val, string)
-        character(len=*), intent(in), optional :: val
+    module subroutine disp_str(value, string)
+        character(len=*), intent(in), optional :: value
         character(len=*), intent(in), optional :: string
     end subroutine disp_str
   end interface disp
diff --git a/src/stdlib_io_disp.fypp b/src/stdlib_io_disp.fypp
index aa4b8e96d..9a3aa617d 100644
--- a/src/stdlib_io_disp.fypp
+++ b/src/stdlib_io_disp.fypp
@@ -4,7 +4,7 @@
 submodule (stdlib_io) stdlib_io_disp
 
     use stdlib_ascii, only: to_string
-    use stdlib_strings, only: format_string
+    use stdlib_strings, only: format_to_string
     implicit none
     character(len=*), parameter :: fmt_r = '(*(g12.4, 1x))'
     character(len=*), parameter :: fmt_c = '(*(g25.0, 1x))'
@@ -13,102 +13,103 @@ contains
     
     #:for kind, type in RIL_KINDS_TYPES
     module procedure disp_0_${type[0]}$${kind}$
-        !! Disp ${type}$ variable to default output_unit
+        !! Display a ${type}$ variable to the default `output_unit`
         if(present(string)) print *, trim(string)
-        print fmt_r, val
+        print fmt_r, value
     end procedure disp_0_${type[0]}$${kind}$
 
     module procedure disp_1_${type[0]}$${kind}$
-        !! Disp ${type}$ vector variable to default output_unit
+        !! Display a ${type}$ vector variable to the default `output_unit`
         if(present(string)) print *, trim(string)
-        print fmt_r, val(:)
+        print fmt_r, value(:)
     end procedure disp_1_${type[0]}$${kind}$
 
     module procedure disp_2_${type[0]}$${kind}$
-        !! Disp ${type}$ 2D array variable to default output_unit
+        !! Display a ${type}$ 2D array variable to the default `output_unit`
         integer :: i, m
-        m = size(val, 1)
+        m = size(value, 1)
         if(present(string)) print *, trim(string)
         do i = 1, m
-            print fmt_r, val(i,:)
+            print fmt_r, value(i,:)
         end do
     end procedure disp_2_${type[0]}$${kind}$
 
     module procedure disp_3_${type[0]}$${kind}$
-        !! Disp ${type}$ 3D array variable to default output_unit
+        !! Display a ${type}$ 3D array variable to the default `output_unit`
         integer :: i, dim1, dim2, dim3
-        dim1 = size(val, 1)
-        dim2 = size(val, 2)
-        dim3 = size(val, 3)
+        dim1 = size(value, 1)
+        dim2 = size(value, 2)
+        dim3 = size(value, 3)
         if(present(string)) print *, trim(string)
-        if(dim == 1) then
+        select case(dim)
+        case(1)
             do i = 1, dim1
                 print *, 'Slice ('//to_string(i)//',:,:):'
-                call disp_2_${type[0]}$${kind}$(val(i, :, :))
+                call disp_2_${type[0]}$${kind}$(value(i, :, :))
             end do
-        elseif(dim == 2) then
+        case(2)
             do i = 1, dim2
                 print *, 'Slice (:,'//to_string(i)//',:):'
-                call disp_2_${type[0]}$${kind}$(val(:, i, :))
+                call disp_2_${type[0]}$${kind}$(value(:, i, :))
             end do
-        elseif (dim == 3) then
+        case(3)
             do i = 1, dim3
                 print *, 'Slice (:,:,'//to_string(i)//'):'
-                call disp_2_${type[0]}$${kind}$(val(:, :, i))
+                call disp_2_${type[0]}$${kind}$(value(:, :, i))
             end do
-        else
+        case default
             call error_stop('Error(disp): wrong dimension')
-        end if
+        end select
     end procedure disp_3_${type[0]}$${kind}$
     #:endfor
 
     #:for kind, type in CMPLX_KINDS_TYPES
     module procedure disp_0_${type[0]}$${kind}$
-        !! Disp ${type}$ variable to default output_unit
+        !! Display a ${type}$ variable to the default `output_unit`
         if(present(string)) print *, trim(string)
-        print fmt_c, format_string(val, '(g0.4)')
+        print fmt_c, format_to_string(value, '(g0.4)')
     end procedure disp_0_${type[0]}$${kind}$
 
     module procedure disp_1_${type[0]}$${kind}$
-        !! Disp ${type}$ vector variable to default output_unit
+        !! Display a ${type}$ vector variable to the default `output_unit`
         integer :: i, m
-        m = size(val)
+        m = size(value)
         if(present(string)) print *, trim(string)
-        print fmt_c, (format_string(val(i), '(g0.4)'), i=1, m)
+        print fmt_c, (format_to_string(value(i), '(g0.4)'), i=1, m)
     end procedure disp_1_${type[0]}$${kind}$
 
     module procedure disp_2_${type[0]}$${kind}$
-        !! Disp ${type}$ 2D array variable to default output_unit
+        !! Display a ${type}$ 2D array variable to the default `output_unit`
         integer :: i, j, m, n
-        m = size(val, 1)
-        n = size(val, 2)
+        m = size(value, 1)
+        n = size(value, 2)
         if(present(string)) print *, trim(string)
         do i = 1, m
-            print fmt_c, (format_string(val(i, j), '(g0.4)'), j=1, n)
+            print fmt_c, (format_to_string(value(i, j), '(g0.4)'), j=1, n)
         end do
     end procedure disp_2_${type[0]}$${kind}$
 
     module procedure disp_3_${type[0]}$${kind}$
-        !! Disp ${type}$ 3D array variable to default output_unit
+        !! Display a ${type}$ 3D array variable to the default `output_unit`
         integer :: i, dim1, dim2, dim3
-        dim1 = size(val, 1)
-        dim2 = size(val, 2)
-        dim3 = size(val, 3)
+        dim1 = size(value, 1)
+        dim2 = size(value, 2)
+        dim3 = size(value, 3)
         if(present(string)) print *, trim(string)
         if(dim == 1) then
             do i = 1, dim1
                 print *, 'Slice ('//to_string(i)//',:,:):'
-                call disp_2_${type[0]}$${kind}$(val(i, :, :))
+                call disp_2_${type[0]}$${kind}$(value(i, :, :))
             end do
         elseif(dim == 2) then
             do i = 1, dim2
                 print *, 'Slice (:,'//to_string(i)//',:):'
-                call disp_2_${type[0]}$${kind}$(val(:, i, :))
+                call disp_2_${type[0]}$${kind}$(value(:, i, :))
             end do
         elseif (dim == 3) then
             do i = 1, dim3
                 print *, 'Slice (:,:,'//to_string(i)//'):'
-                call disp_2_${type[0]}$${kind}$(val(:, :, i))
+                call disp_2_${type[0]}$${kind}$(value(:, :, i))
             end do
         else
             call error_stop('Error(disp): wrong dimension')
@@ -117,10 +118,10 @@ contains
     #:endfor
 
     module procedure disp_str
-        !! Disp character variable to default output_unit
+        !! Display a character variable to the default `output_unit`
         if(present(string)) print *, trim(string)
-        if(present(val)) then
-            print *, trim(val)
+        if(present(value)) then
+            print *, trim(value)
         else
             print *, ''
         end if

From 3b0f0bc9a9e43765af100a1f2e53a1b7d8a9485f Mon Sep 17 00:00:00 2001
From: zoziha13 <1325686572@qq.com>
Date: Wed, 7 Jul 2021 17:49:13 +0800
Subject: [PATCH 04/14] Update `disp`: add optional `unit` and `brief`.

---
 doc/specs/stdlib_io.md        |  84 +++++++-------
 src/stdlib_io.fypp            |  19 ++--
 src/stdlib_io_disp.fypp       | 199 +++++++++++++++++++---------------
 src/tests/io/test_io_disp.f90 |  26 +++--
 4 files changed, 185 insertions(+), 143 deletions(-)

diff --git a/doc/specs/stdlib_io.md b/doc/specs/stdlib_io.md
index 8c2c486c1..e77c776d3 100644
--- a/doc/specs/stdlib_io.md
+++ b/doc/specs/stdlib_io.md
@@ -132,18 +132,18 @@ program demo_savetxt
 end program demo_savetxt
 ```
 
-## `disp` - display your data to the screen (or the default `output_unit`)
+## `disp` - display your data to the screen (or an other output unit)
 
 ### Status
 
 Experimental
 
 ### Description
-Display any type of scalar or `array` with up to 3 dimensions to the screen (or the default `output_unit`).  
+Display any type of scalar, vector or matrix.
 
 Make good use of similar to the following usage, can help you understand the data information in the `array`.
 ```fortran
-call disp( A(i, j, 2, :, :) [, string] )    !! `i, j, ...` can be determined by `do` loop.
+call disp( A(i, j, 2, :, :) [, unit, header, brief] )    !! `i, j, ...` can be determined by `do` loop.
 ```
 
 Generally, except for `complex` type, any other type of scalar or single element of the `array` will be printed out with a width of 12 characters and a space separator.  
@@ -152,40 +152,41 @@ For `complex` type, scalar or single element of the `array` will be printed out
 ### Syntax
 
 General API:
-`call [[stdlib_io(module):disp(interface)]](value [, string])`
-
-Except, for 3D arrays:
-`call [[stdlib_io(module):disp(interface)]](value, dim [, string])` 
+`call [[stdlib_io(module):disp(interface)]](value [, unit, header, brief])`
 
 For null:
 `call [[stdlib_io(module):disp(interface)]]()`  
 
 ### Arguments
 
-`value`: Shall be any type of scalar or `array` with up to 3 dimensions.
+`value`: Shall be any type of scalar, vector or matrix.
     This is an `intent(in)` argument.
 
-`dim`: Shall be a scalar of type `integer` with a value: 1, 2 or 3.
-    This is an `intent(in)` argument.
+`unit`: Shall be an `integer` scalar link to an IO stream.
+    This is an `intent(in)` and `optional` argument.
+
+`header`: Shall be a scalar of type `character` with any length (usually used to comment data information).
+    This is an `intent(in)` and `optional` argument.
 
-`string`: Shall be a scalar of type `character` with any length (usually used to comment data information).
+`brief`: Shall be an `logical` scalar, controling an abridged version of the `value` object is printed.
     This is an `intent(in)` and `optional` argument.
 
 ### Output
 
-The result is to print `string` and `value` on the screen (or the default `output_unit`) in this order.
+The result is to print `header` and `value` on the screen (or an other output unit) in this order.  
+If `value` is a `array` type, the dimension length information of the `array` will also be output.
 
 ### Example
 
 ```fortran
-program demo_io_disp
-
+program test_io_disp
+    
     use :: stdlib_io, only: disp
     implicit none
     real(8) :: r(2, 3)
-    complex :: c(2, 3), c_3d(2, 3, 2)
+    complex :: c(2, 3), c_3d(2, 100, 20)
     integer :: i(2, 3)
-    logical :: l(2, 3)
+    logical :: l(10, 10)
 
     r = 1.; c = 1.; c_3d = 2.; i = 1; l = .true.
     r(1, 1) = -1.e-11
@@ -193,47 +194,54 @@ program demo_io_disp
     c(2, 2) = (-1.e10,-1.e10)
     c_3d(1,3,1) = (1000, 0.001)
     c_3d(1,3,2) = (1.e4, 100.)
-
-    call disp('string', 'disp(string):')
+    call disp('string', header='disp(string):')
     call disp('It is a note.')
     call disp()
 
-    call disp(r, 'disp(r):')
-    call disp(c, 'disp(c):')
-    call disp(i(1,:), 'disp(i):')
-    call disp(l(:,2), 'disp(l):')
+    call disp(r, header='disp(r):')
+    call disp(c, header='disp(c):')
+    call disp(i, header='disp(i):')
+    call disp(l, header='disp(l):', brief=.true.)
 
-    call disp(c_3d, 3, 'disp(c_3d, 3):')
+    call disp(c_3d(:,:,3), header='disp(c_3d, 3):', brief=.true.)
+    call disp(c_3d(2,:,:), header='disp(c_3d, 2):', brief=.true.)
 
-    call disp(c_3d(1,:,:), 'disp(c_3d(1,:,:)):')
-    
-end program demo_io_disp
+end program test_io_disp
 ```
 **Result:**
 ```fortran
- disp(string):
+disp(string):
  string
  It is a note.
 
  disp(r):
+ [matrix size: 2×3]
  -0.1000E-10  -0.1000E+11    1.000
    1.000        1.000        1.000
  disp(c):
+ [matrix size: 2×3]
             (1.000,0.000)             (1.000,0.000)             (1.000,0.000)
             (1.000,0.000) (-0.1000E+11,-0.1000E+11)             (1.000,0.000)
  disp(i):
+ [matrix size: 2×3]
+           1            1            1
            1            1            1
  disp(l):
-           T            T
+ [matrix size: 10×10]
+           T            T            T          ...            T
+           T            T            T          ...            T
+           T            T            T          ...            T
+           :            :            :            :            :
+           T            T            T          ...            T
  disp(c_3d, 3):
- Slice (:,:,1):
-            (2.000,0.000)             (2.000,0.000)         (1000.,0.1000E-2)
-            (2.000,0.000)             (2.000,0.000)             (2.000,0.000)
- Slice (:,:,2):
-            (2.000,0.000)             (2.000,0.000)         (0.1000E+5,100.0)
-            (2.000,0.000)             (2.000,0.000)             (2.000,0.000)
- disp(c_3d(1,:,:)):
-            (2.000,0.000)             (2.000,0.000)
-            (2.000,0.000)             (2.000,0.000)
-        (1000.,0.1000E-2)         (0.1000E+5,100.0)
+ [matrix size: 2×100]
+            (2.000,0.000)             (2.000,0.000)             (2.000,0.000)                       ...             (2.000,0.000)  
+            (2.000,0.000)             (2.000,0.000)             (2.000,0.000)                       ...             (2.000,0.000)  
+ disp(c_3d, 2):
+ [matrix size: 100×20]
+            (2.000,0.000)             (2.000,0.000)             (2.000,0.000)                       ...             (2.000,0.000)  
+            (2.000,0.000)             (2.000,0.000)             (2.000,0.000)                       ...             (2.000,0.000)  
+            (2.000,0.000)             (2.000,0.000)             (2.000,0.000)                       ...             (2.000,0.000)  
+                        :                         :                         :                         :                         :  
+            (2.000,0.000)             (2.000,0.000)             (2.000,0.000)                       ...             (2.000,0.000) 
 ```
diff --git a/src/stdlib_io.fypp b/src/stdlib_io.fypp
index 002b7b021..e94fdcc48 100644
--- a/src/stdlib_io.fypp
+++ b/src/stdlib_io.fypp
@@ -22,23 +22,26 @@ module stdlib_io
   interface disp
     !! version: experimental
     !!
-    !! Display any type of scalar and `array` with up to 3 dimensions to the default `output_unit`
-    !! ([Specification](../page/specs/stdlib_io.html#description_4))
+    !! Display any type of scalar, vector and matrix.
+    !! ([Specification](../page/specs/stdlib_io.html))
     #:set DISP_KINDS_TYPES = REAL_KINDS_TYPES + INT_KINDS_TYPES &
         & + CMPLX_KINDS_TYPES + LOG_KINDS_TYPES
-    #:set DISP_RANKS = range(0, 4)
+    #:set DISP_RANKS = range(0, 3)
     #:for kind, type in DISP_KINDS_TYPES
     #:for rank in DISP_RANKS
-    module subroutine disp_${rank}$_${type[0]}$${kind}$(value, #{if rank == 3}#dim, #{endif}#string)
+    module subroutine disp_${rank}$_${type[0]}$${kind}$(value, unit, header, brief)
         ${type}$, intent(in) :: value${ranksuffix(rank)}$
-        #{if rank == 3}#integer, intent(in) :: dim#{endif}#
-        character(len=*), intent(in), optional :: string
+        integer, intent(in), optional :: unit
+        character(len=*), intent(in), optional :: header
+        logical, intent(in), optional :: brief
     end subroutine disp_${rank}$_${type[0]}$${kind}$
     #:endfor
     #:endfor
-    module subroutine disp_str(value, string)
+    module subroutine disp_str(value, unit, header, brief)
         character(len=*), intent(in), optional :: value
-        character(len=*), intent(in), optional :: string
+        integer, intent(in), optional :: unit
+        character(len=*), intent(in), optional :: header
+        logical, intent(in), optional :: brief
     end subroutine disp_str
   end interface disp
 
diff --git a/src/stdlib_io_disp.fypp b/src/stdlib_io_disp.fypp
index 9a3aa617d..027d29677 100644
--- a/src/stdlib_io_disp.fypp
+++ b/src/stdlib_io_disp.fypp
@@ -5,6 +5,7 @@ submodule (stdlib_io) stdlib_io_disp
 
     use stdlib_ascii, only: to_string
     use stdlib_strings, only: format_to_string
+    use, intrinsic :: iso_fortran_env, only: output_unit
     implicit none
     character(len=*), parameter :: fmt_r = '(*(g12.4, 1x))'
     character(len=*), parameter :: fmt_c = '(*(g25.0, 1x))'
@@ -13,118 +14,146 @@ contains
     
     #:for kind, type in RIL_KINDS_TYPES
     module procedure disp_0_${type[0]}$${kind}$
-        !! Display a ${type}$ variable to the default `output_unit`
-        if(present(string)) print *, trim(string)
-        print fmt_r, value
+        !! Display a/an ${type}$ scalar.
+        integer :: unit_
+        unit_  = merge(unit, output_unit, present(unit))
+        if(present(header)) write(unit_, *) header
+        write(unit_, fmt_r) value
     end procedure disp_0_${type[0]}$${kind}$
 
     module procedure disp_1_${type[0]}$${kind}$
-        !! Display a ${type}$ vector variable to the default `output_unit`
-        if(present(string)) print *, trim(string)
-        print fmt_r, value(:)
+        !! Display a/an ${type}$ vector.
+        integer :: unit_
+        logical :: brief_
+        integer :: m
+        unit_  = merge(unit, output_unit, present(unit))
+        brief_ = merge(brief, .false., present(brief))
+        m = size(value, 1)
+        if(present(header)) write(unit_, *) header
+        write(unit_, *) '[vector size: '//to_string(m)//']'
+        if(brief_ .and. m > 5) then
+            write(unit_, fmt_r) value(1:3), '...', value(m)
+        else
+            write(unit_, fmt_r) value(:)
+        end if
     end procedure disp_1_${type[0]}$${kind}$
 
     module procedure disp_2_${type[0]}$${kind}$
-        !! Display a ${type}$ 2D array variable to the default `output_unit`
-        integer :: i, m
+        !! Display a/an ${type}$ matrix.
+        integer :: unit_
+        logical :: brief_
+        character(1) :: colon(5)
+        integer :: i, m, n
+        unit_  = merge(unit, output_unit, present(unit))
+        brief_ = merge(brief, .false., present(brief))
         m = size(value, 1)
-        if(present(string)) print *, trim(string)
-        do i = 1, m
-            print fmt_r, value(i,:)
-        end do
-    end procedure disp_2_${type[0]}$${kind}$
-
-    module procedure disp_3_${type[0]}$${kind}$
-        !! Display a ${type}$ 3D array variable to the default `output_unit`
-        integer :: i, dim1, dim2, dim3
-        dim1 = size(value, 1)
-        dim2 = size(value, 2)
-        dim3 = size(value, 3)
-        if(present(string)) print *, trim(string)
-        select case(dim)
-        case(1)
-            do i = 1, dim1
-                print *, 'Slice ('//to_string(i)//',:,:):'
-                call disp_2_${type[0]}$${kind}$(value(i, :, :))
-            end do
-        case(2)
-            do i = 1, dim2
-                print *, 'Slice (:,'//to_string(i)//',:):'
-                call disp_2_${type[0]}$${kind}$(value(:, i, :))
-            end do
-        case(3)
-            do i = 1, dim3
-                print *, 'Slice (:,:,'//to_string(i)//'):'
-                call disp_2_${type[0]}$${kind}$(value(:, :, i))
+        n = size(value, 2)
+        if(present(header)) write(unit_, *) header
+        write(unit_, *) '[matrix size: '//to_string(m)//'×'//to_string(n)//']'
+        if(brief_ .and. (m > 5 .or. n > 5)) then
+            if(m > 5 .and. n > 5) then
+                do i = 1, 3
+                    write(unit_, fmt_r) value(i,1:3), '...', value(i,n)
+                end do
+                write(unit_, fmt_r) ':', ':', ':', ':', ':'
+                write(unit_, fmt_r) value(m,1:3), '...', value(m,n)
+            elseif(m > 5 .and. n <= 5) then
+                do i = 1, 3
+                    write(unit_, fmt_r) value(i,:)
+                end do
+                colon(1:n) = ':'
+                write(unit_, fmt_r) colon(1:n)
+                write(unit_, fmt_r) value(m,:)
+            elseif(m <= 5 .and. n > 5) then
+                do i = 1, m
+                    write(unit_, fmt_r) value(i,1:3), '...', value(i,n)
+                end do
+            end if
+        else
+            do i = 1, m
+                write(unit_, fmt_r) value(i,:)
             end do
-        case default
-            call error_stop('Error(disp): wrong dimension')
-        end select
-    end procedure disp_3_${type[0]}$${kind}$
+        end if
+    end procedure disp_2_${type[0]}$${kind}$
     #:endfor
 
     #:for kind, type in CMPLX_KINDS_TYPES
     module procedure disp_0_${type[0]}$${kind}$
-        !! Display a ${type}$ variable to the default `output_unit`
-        if(present(string)) print *, trim(string)
-        print fmt_c, format_to_string(value, '(g0.4)')
+        !! Display a ${type}$ scalar.
+        integer :: unit_
+        unit_  = merge(unit, output_unit, present(unit))
+        if(present(header)) write(unit_, *) header
+        write(unit_, fmt_c) format_to_string(value, '(g0.4)')
     end procedure disp_0_${type[0]}$${kind}$
 
     module procedure disp_1_${type[0]}$${kind}$
-        !! Display a ${type}$ vector variable to the default `output_unit`
+        !! Display a ${type}$ vector.
+        integer :: unit_
+        logical :: brief_
         integer :: i, m
-        m = size(value)
-        if(present(string)) print *, trim(string)
-        print fmt_c, (format_to_string(value(i), '(g0.4)'), i=1, m)
+        unit_  = merge(unit, output_unit, present(unit))
+        brief_ = merge(brief, .false., present(brief))
+        m = size(value, 1)
+        if(present(header)) write(unit_, *) header
+        write(unit_, *) '[vector size: '//to_string(m)//']'
+        if(brief_ .and. m > 5) then
+            write(unit_, fmt_c) (format_to_string(value(i), '(g0.4)'), i=1, 3), &
+                          '...', format_to_string(value(m), '(g0.4)')
+        else
+            write(unit_, fmt_c) (format_to_string(value(i), '(g0.4)'), i=1, m)
+        end if
     end procedure disp_1_${type[0]}$${kind}$
 
     module procedure disp_2_${type[0]}$${kind}$
-        !! Display a ${type}$ 2D array variable to the default `output_unit`
+        !! Display a ${type}$ matrix.
+        integer :: unit_
+        logical :: brief_
+        character(1) :: colon(5)
         integer :: i, j, m, n
+        unit_  = merge(unit, output_unit, present(unit))
+        brief_ = merge(brief, .false., present(brief))
         m = size(value, 1)
         n = size(value, 2)
-        if(present(string)) print *, trim(string)
-        do i = 1, m
-            print fmt_c, (format_to_string(value(i, j), '(g0.4)'), j=1, n)
-        end do
-    end procedure disp_2_${type[0]}$${kind}$
-
-    module procedure disp_3_${type[0]}$${kind}$
-        !! Display a ${type}$ 3D array variable to the default `output_unit`
-        integer :: i, dim1, dim2, dim3
-        dim1 = size(value, 1)
-        dim2 = size(value, 2)
-        dim3 = size(value, 3)
-        if(present(string)) print *, trim(string)
-        if(dim == 1) then
-            do i = 1, dim1
-                print *, 'Slice ('//to_string(i)//',:,:):'
-                call disp_2_${type[0]}$${kind}$(value(i, :, :))
-            end do
-        elseif(dim == 2) then
-            do i = 1, dim2
-                print *, 'Slice (:,'//to_string(i)//',:):'
-                call disp_2_${type[0]}$${kind}$(value(:, i, :))
-            end do
-        elseif (dim == 3) then
-            do i = 1, dim3
-                print *, 'Slice (:,:,'//to_string(i)//'):'
-                call disp_2_${type[0]}$${kind}$(value(:, :, i))
-            end do
+        if(present(header)) write(unit_, *) header
+        write(unit_, *) '[matrix size: '//to_string(m)//'×'//to_string(n)//']'
+        if(brief_ .and. (m > 5 .or. n > 5)) then
+            if(m > 5 .and. n > 5) then
+                do i = 1, 3
+                    write(unit_, fmt_c) (format_to_string(value(i,j), '(g0.4)'), j=1, 3), &
+                                  '...', format_to_string(value(i,n), '(g0.4)')
+                end do
+                write(unit_, fmt_c) ':', ':', ':', ':', ':'
+                write(unit_, fmt_c) (format_to_string(value(m,j), '(g0.4)'), j=1, 3), &
+                              '...', format_to_string(value(m,n), '(g0.4)')
+            elseif(m > 5 .and. n <= 5) then
+                do i = 1, 3
+                    write(unit_, fmt_c) (format_to_string(value(i,j), '(g0.4)'), j=1, n)
+                end do
+                colon(1:n) = ':'
+                write(unit_, fmt_c) colon(1:n)
+                write(unit_, fmt_c) (format_to_string(value(m,j), '(g0.4)'), j=1, n)
+            elseif(m <= 5 .and. n > 5) then
+                do i = 1, m
+                    write(unit_, fmt_c) (format_to_string(value(m,j), '(g0.4)'), j=1, 3), &
+                                  '...', format_to_string(value(m,n), '(g0.4)')
+                end do
+            end if
         else
-            call error_stop('Error(disp): wrong dimension')
+            do i = 1, m
+                write(unit_, fmt_c) (format_to_string(value(i,j), '(g0.4)'), j=1, n)
+            end do
         end if
-    end procedure disp_3_${type[0]}$${kind}$
+    end procedure disp_2_${type[0]}$${kind}$
     #:endfor
 
     module procedure disp_str
-        !! Display a character variable to the default `output_unit`
-        if(present(string)) print *, trim(string)
-        if(present(value)) then
-            print *, trim(value)
-        else
-            print *, ''
-        end if
+        !! Display a `character` scalar.
+        character(:), allocatable :: value_
+        integer :: unit_
+        value_ = optval(value, '')
+        unit_  = merge(unit, output_unit, present(unit))
+        if(present(header)) write(unit_, *) header
+        write(unit_, *) value_
     end procedure disp_str
 
 end submodule stdlib_io_disp
\ No newline at end of file
diff --git a/src/tests/io/test_io_disp.f90 b/src/tests/io/test_io_disp.f90
index 6bb7ccfec..c17284fc6 100644
--- a/src/tests/io/test_io_disp.f90
+++ b/src/tests/io/test_io_disp.f90
@@ -1,10 +1,11 @@
 program test_io_disp
-    use, non_intrinsic :: stdlib_io, only: disp
+    
+    use :: stdlib_io, only: disp
     implicit none
     real(8) :: r(2, 3)
-    complex :: c(2, 3), c_3d(2, 3, 2)
+    complex :: c(2, 3), c_3d(2, 100, 20)
     integer :: i(2, 3)
-    logical :: l(2, 3)
+    logical :: l(10, 10)
 
     r = 1.; c = 1.; c_3d = 2.; i = 1; l = .true.
     r(1, 1) = -1.e-11
@@ -12,15 +13,16 @@ program test_io_disp
     c(2, 2) = (-1.e10,-1.e10)
     c_3d(1,3,1) = (1000, 0.001)
     c_3d(1,3,2) = (1.e4, 100.)
-        call disp('string', 'disp(string):')
-        call disp('It is a note.')
-        call disp()
+    call disp('string', header='disp(string):')
+    call disp('It is a note.')
+    call disp()
 
-        call disp(r, 'disp(r):')
-        call disp(c, 'disp(c):')
-        call disp(i, 'disp(i):')
-        call disp(l, 'disp(l):')
+    call disp(r, header='disp(r):')
+    call disp(c, header='disp(c):')
+    call disp(i, header='disp(i):')
+    call disp(l, header='disp(l):', brief=.true.)
+
+    call disp(c_3d(:,:,3), header='disp(c_3d, 3):', brief=.true.)
+    call disp(c_3d(2,:,:), header='disp(c_3d, 2):', brief=.true.)
 
-        call disp(c_3d, 3, 'disp(c_3d, 3):')
-        call disp(c_3d, 2, 'disp(c_3d, 2):')
 end program test_io_disp
\ No newline at end of file

From 652aad849ec552fc44dd693356f711b682ee7d32 Mon Sep 17 00:00:00 2001
From: zoziha13 <1325686572@qq.com>
Date: Wed, 7 Jul 2021 17:51:56 +0800
Subject: [PATCH 05/14] an other -> another

---
 doc/specs/stdlib_io.md | 4 ++--
 1 file changed, 2 insertions(+), 2 deletions(-)

diff --git a/doc/specs/stdlib_io.md b/doc/specs/stdlib_io.md
index e77c776d3..e1c61fd18 100644
--- a/doc/specs/stdlib_io.md
+++ b/doc/specs/stdlib_io.md
@@ -132,7 +132,7 @@ program demo_savetxt
 end program demo_savetxt
 ```
 
-## `disp` - display your data to the screen (or an other output unit)
+## `disp` - display your data to the screen (or another output unit)
 
 ### Status
 
@@ -173,7 +173,7 @@ For null:
 
 ### Output
 
-The result is to print `header` and `value` on the screen (or an other output unit) in this order.  
+The result is to print `header` and `value` on the screen (or another output unit) in this order.  
 If `value` is a `array` type, the dimension length information of the `array` will also be output.
 
 ### Example

From f10333d7f0953ceabb3419bafe01f20cb05bde89 Mon Sep 17 00:00:00 2001
From: zoziha13 <1325686572@qq.com>
Date: Sat, 10 Jul 2021 13:48:47 +0800
Subject: [PATCH 06/14] Add a valid `test_io_disp.f90`

---
 doc/specs/stdlib_io.md        |  18 +-
 src/stdlib_io_disp.fypp       |  27 +--
 src/tests/io/test_io_disp.f90 | 404 +++++++++++++++++++++++++++++++---
 3 files changed, 402 insertions(+), 47 deletions(-)

diff --git a/doc/specs/stdlib_io.md b/doc/specs/stdlib_io.md
index e1c61fd18..4bea7d810 100644
--- a/doc/specs/stdlib_io.md
+++ b/doc/specs/stdlib_io.md
@@ -143,7 +143,7 @@ Display any type of scalar, vector or matrix.
 
 Make good use of similar to the following usage, can help you understand the data information in the `array`.
 ```fortran
-call disp( A(i, j, 2, :, :) [, unit, header, brief] )    !! `i, j, ...` can be determined by `do` loop.
+call disp( A(i, j, 2, :, 1:10) [, unit, header, brief] )    !! `i, j, ...` can be determined by `do` loop.
 ```
 
 Generally, except for `complex` type, any other type of scalar or single element of the `array` will be printed out with a width of 12 characters and a space separator.  
@@ -174,7 +174,7 @@ For null:
 ### Output
 
 The result is to print `header` and `value` on the screen (or another output unit) in this order.  
-If `value` is a `array` type, the dimension length information of the `array` will also be output.
+If `value` is a `array` type, the dimension length information of the `array` will also be outputed.
 
 ### Example
 
@@ -199,18 +199,19 @@ program test_io_disp
     call disp()
 
     call disp(r, header='disp(r):')
+    call disp(r(1,:), header='disp(r(1,:))')
     call disp(c, header='disp(c):')
     call disp(i, header='disp(i):')
     call disp(l, header='disp(l):', brief=.true.)
 
-    call disp(c_3d(:,:,3), header='disp(c_3d, 3):', brief=.true.)
-    call disp(c_3d(2,:,:), header='disp(c_3d, 2):', brief=.true.)
+    call disp(c_3d(:,:,3), header='disp(c_3d(:,:,3)):', brief=.true.)
+    call disp(c_3d(2,:,:), header='disp(c_3d(2,:,:)):', brief=.true.)
 
 end program test_io_disp
 ```
 **Result:**
 ```fortran
-disp(string):
+ disp(string):
  string
  It is a note.
 
@@ -218,6 +219,9 @@ disp(string):
  [matrix size: 2×3]
  -0.1000E-10  -0.1000E+11    1.000
    1.000        1.000        1.000
+ disp(r(1,:))
+ [vector size: 3]
+ -0.1000E-10  -0.1000E+11    1.000
  disp(c):
  [matrix size: 2×3]
             (1.000,0.000)             (1.000,0.000)             (1.000,0.000)
@@ -233,11 +237,11 @@ disp(string):
            T            T            T          ...            T
            :            :            :            :            :
            T            T            T          ...            T
- disp(c_3d, 3):
+ disp(c_3d(:,:,3)):
  [matrix size: 2×100]
             (2.000,0.000)             (2.000,0.000)             (2.000,0.000)                       ...             (2.000,0.000)  
             (2.000,0.000)             (2.000,0.000)             (2.000,0.000)                       ...             (2.000,0.000)  
- disp(c_3d, 2):
+ disp(c_3d(2,:,:)):
  [matrix size: 100×20]
             (2.000,0.000)             (2.000,0.000)             (2.000,0.000)                       ...             (2.000,0.000)  
             (2.000,0.000)             (2.000,0.000)             (2.000,0.000)                       ...             (2.000,0.000)  
diff --git a/src/stdlib_io_disp.fypp b/src/stdlib_io_disp.fypp
index 027d29677..e6ccf3871 100644
--- a/src/stdlib_io_disp.fypp
+++ b/src/stdlib_io_disp.fypp
@@ -9,6 +9,7 @@ submodule (stdlib_io) stdlib_io_disp
     implicit none
     character(len=*), parameter :: fmt_r = '(*(g12.4, 1x))'
     character(len=*), parameter :: fmt_c = '(*(g25.0, 1x))'
+    character(len=*), parameter :: format_ = '(g0.4)'
     
 contains
     
@@ -83,7 +84,7 @@ contains
         integer :: unit_
         unit_  = merge(unit, output_unit, present(unit))
         if(present(header)) write(unit_, *) header
-        write(unit_, fmt_c) format_to_string(value, '(g0.4)')
+        write(unit_, fmt_c) format_to_string(value, format_)
     end procedure disp_0_${type[0]}$${kind}$
 
     module procedure disp_1_${type[0]}$${kind}$
@@ -97,10 +98,10 @@ contains
         if(present(header)) write(unit_, *) header
         write(unit_, *) '[vector size: '//to_string(m)//']'
         if(brief_ .and. m > 5) then
-            write(unit_, fmt_c) (format_to_string(value(i), '(g0.4)'), i=1, 3), &
-                          '...', format_to_string(value(m), '(g0.4)')
+            write(unit_, fmt_c) (format_to_string(value(i), format_), i=1, 3), &
+                          '...', format_to_string(value(m), format_)
         else
-            write(unit_, fmt_c) (format_to_string(value(i), '(g0.4)'), i=1, m)
+            write(unit_, fmt_c) (format_to_string(value(i), format_), i=1, m)
         end if
     end procedure disp_1_${type[0]}$${kind}$
 
@@ -119,28 +120,28 @@ contains
         if(brief_ .and. (m > 5 .or. n > 5)) then
             if(m > 5 .and. n > 5) then
                 do i = 1, 3
-                    write(unit_, fmt_c) (format_to_string(value(i,j), '(g0.4)'), j=1, 3), &
-                                  '...', format_to_string(value(i,n), '(g0.4)')
+                    write(unit_, fmt_c) (format_to_string(value(i,j), format_), j=1, 3), &
+                                  '...', format_to_string(value(i,n), format_)
                 end do
                 write(unit_, fmt_c) ':', ':', ':', ':', ':'
-                write(unit_, fmt_c) (format_to_string(value(m,j), '(g0.4)'), j=1, 3), &
-                              '...', format_to_string(value(m,n), '(g0.4)')
+                write(unit_, fmt_c) (format_to_string(value(m,j), format_), j=1, 3), &
+                              '...', format_to_string(value(m,n), format_)
             elseif(m > 5 .and. n <= 5) then
                 do i = 1, 3
-                    write(unit_, fmt_c) (format_to_string(value(i,j), '(g0.4)'), j=1, n)
+                    write(unit_, fmt_c) (format_to_string(value(i,j), format_), j=1, n)
                 end do
                 colon(1:n) = ':'
                 write(unit_, fmt_c) colon(1:n)
-                write(unit_, fmt_c) (format_to_string(value(m,j), '(g0.4)'), j=1, n)
+                write(unit_, fmt_c) (format_to_string(value(m,j), format_), j=1, n)
             elseif(m <= 5 .and. n > 5) then
                 do i = 1, m
-                    write(unit_, fmt_c) (format_to_string(value(m,j), '(g0.4)'), j=1, 3), &
-                                  '...', format_to_string(value(m,n), '(g0.4)')
+                    write(unit_, fmt_c) (format_to_string(value(m,j), format_), j=1, 3), &
+                                  '...', format_to_string(value(m,n), format_)
                 end do
             end if
         else
             do i = 1, m
-                write(unit_, fmt_c) (format_to_string(value(i,j), '(g0.4)'), j=1, n)
+                write(unit_, fmt_c) (format_to_string(value(i,j), format_), j=1, n)
             end do
         end if
     end procedure disp_2_${type[0]}$${kind}$
diff --git a/src/tests/io/test_io_disp.f90 b/src/tests/io/test_io_disp.f90
index c17284fc6..c65be16dd 100644
--- a/src/tests/io/test_io_disp.f90
+++ b/src/tests/io/test_io_disp.f90
@@ -1,28 +1,378 @@
-program test_io_disp
-    
-    use :: stdlib_io, only: disp
+module test_io_disp
+
+    use stdlib_strings, only: starts_with
+    use stdlib_error, only: check
+    use stdlib_io, only: disp, open
     implicit none
-    real(8) :: r(2, 3)
-    complex :: c(2, 3), c_3d(2, 100, 20)
-    integer :: i(2, 3)
-    logical :: l(10, 10)
-
-    r = 1.; c = 1.; c_3d = 2.; i = 1; l = .true.
-    r(1, 1) = -1.e-11
-    r(1, 2) = -1.e10
-    c(2, 2) = (-1.e10,-1.e10)
-    c_3d(1,3,1) = (1000, 0.001)
-    c_3d(1,3,2) = (1.e4, 100.)
-    call disp('string', header='disp(string):')
-    call disp('It is a note.')
-    call disp()
-
-    call disp(r, header='disp(r):')
-    call disp(c, header='disp(c):')
-    call disp(i, header='disp(i):')
-    call disp(l, header='disp(l):', brief=.true.)
-
-    call disp(c_3d(:,:,3), header='disp(c_3d, 3):', brief=.true.)
-    call disp(c_3d(2,:,:), header='disp(c_3d, 2):', brief=.true.)
-
-end program test_io_disp
\ No newline at end of file
+
+    integer :: unit
+    character(*), parameter :: filenanme = "./test_io_disp.tmp"
+    character(len=512) :: string
+
+contains
+
+    subroutine check_formatter(actual, expected, description, partial)
+        character(len=*), intent(in) :: actual, expected, description
+        logical, intent(in), optional :: partial
+        logical :: stat
+        character(len=:), allocatable :: msg
+
+        if (merge(partial, .false., present(partial))) then
+            stat = starts_with(actual, expected)
+        else
+            stat = actual == expected
+        end if
+
+        if (.not. stat) then
+            msg = description//new_line("a")// &
+                & "Expected: '"//expected//"' but got '"//actual//"'"
+        else
+            print '(" - ", a, /, "   Result: ''", a, "''")', description, actual
+        end if
+
+        call check(stat, msg)
+
+    end subroutine check_formatter
+
+    subroutine test_io_disp_complex
+        complex :: c(6,6) = (1.0, 1.0)
+        ! unit = open(filenanme, 'w+t')
+        open(newunit=unit, file=filenanme)
+        call disp(c(1,1), header='Test_io_disp_complex_scalar (brief) : ', brief=.true.)
+        call disp(c(1,1), unit=unit, header='Test_io_disp_complex_scalar (brief) : ', brief=.true.)
+
+        call disp(c(1,:), header='Test_io_disp_complex_vector (brief) : ', brief=.true.)
+        call disp(c(1,:), unit=unit, header='Test_io_disp_complex_vector (brief) : ', brief=.true.)
+
+        call disp(c(:,1), header='Test_io_disp_complex_vector : ', brief=.false.)
+        call disp(c(:,1), unit=unit, header='Test_io_disp_complex_vector : ', brief=.false.)
+
+        call disp(c(1:2,1:2), header='Test_io_disp_complex_matrix : ', brief=.false.)
+        call disp(c(1:2,1:2), unit=unit, header='Test_io_disp_complex_matrix : ', brief=.false.)
+
+        call disp(c(:,:), header='Test_io_disp_complex_matrix (brief) : ', brief=.true.)
+        call disp(c(:,:), unit=unit, header='Test_io_disp_complex_matrix (brief) : ', brief=.true.)
+    
+        !! Checks
+        rewind(unit)
+        read(unit, '(A200)') string
+        call check_formatter(trim(adjustl(string)), 'Test_io_disp_complex_scalar (brief) :', 'Header')
+        read(unit, '(A200)') string
+        call check_formatter(trim(adjustl(string)), '(1.000,1.000)', 'Value')
+        
+        read(unit, '(A200)') string
+        call check_formatter(trim(adjustl(string)), 'Test_io_disp_complex_vector (brief) :', 'Header')
+        read(unit, '(A200)') string
+        call check_formatter(trim(adjustl(string)), '[vector size: 6]', 'Vector Info')
+        read(unit, '(A200)') string
+        call check_formatter(trim(adjustl(string)), &
+        '(1.000,1.000)             (1.000,1.000)             (1.000,1.000)  &
+        &                     ...             (1.000,1.000)', 'Brief Vector')
+
+        read(unit, '(A200)') string
+        call check_formatter(trim(adjustl(string)), 'Test_io_disp_complex_vector :', 'Header')
+        read(unit, '(A200)') string
+        call check_formatter(trim(adjustl(string)), '[vector size: 6]', 'Vector Info')
+        read(unit, '(A200)') string
+        call check_formatter(trim(adjustl(string)), &
+        '(1.000,1.000)             (1.000,1.000)             (1.000,1.000)    &
+        &         (1.000,1.000)             (1.000,1.000)             (1.000,1.000)', 'Brief Vector')
+
+        read(unit, '(A200)') string
+        call check_formatter(trim(adjustl(string)), 'Test_io_disp_complex_matrix :', 'Header')
+        read(unit, '(A200)') string
+        call check_formatter(trim(adjustl(string)), '[matrix size: 2×2]', 'Matrix Info')
+        read(unit, '(A200)') string
+        call check_formatter(trim(adjustl(string)), &
+        '(1.000,1.000)             (1.000,1.000)', 'Matrix Vector 1')
+        read(unit, '(A200)') string
+        call check_formatter(trim(adjustl(string)), &
+        '(1.000,1.000)             (1.000,1.000)', 'Matrix Vector 2')
+
+        read(unit, '(A200)') string
+        call check_formatter(trim(adjustl(string)), 'Test_io_disp_complex_matrix (brief) :', 'Header')
+        read(unit, '(A200)') string
+        call check_formatter(trim(adjustl(string)), '[matrix size: 6×6]', 'Matrix Info')
+        read(unit, '(A200)') string
+        call check_formatter(trim(adjustl(string)), &
+        '(1.000,1.000)             (1.000,1.000)             (1.000,1.000)    &
+        &                   ...             (1.000,1.000)', 'Matrix Vector 1')
+        read(unit, '(A200)') string
+        call check_formatter(trim(adjustl(string)), &
+        '(1.000,1.000)             (1.000,1.000)             (1.000,1.000)    &
+        &                   ...             (1.000,1.000)', 'Matrix Vector 2')
+        read(unit, '(A200)') string
+        call check_formatter(trim(adjustl(string)), &
+        '(1.000,1.000)             (1.000,1.000)             (1.000,1.000)    &
+        &                   ...             (1.000,1.000)', 'Matrix Vector 3')
+        read(unit, '(A200)') string
+        call check_formatter(trim(adjustl(string)), &
+        ':                         :                         :                &
+        &         :                         :', 'Matrix Vector ..')
+        read(unit, '(A200)') string
+        call check_formatter(trim(adjustl(string)), &
+        '(1.000,1.000)             (1.000,1.000)             (1.000,1.000)    &
+        &                   ...             (1.000,1.000)', 'Matrix Vector Size(Matrix, 1)')
+        close(unit)
+
+    end subroutine test_io_disp_complex
+
+    subroutine test_io_disp_real
+
+        real :: r(6,6) = 1.0
+        ! unit = open(filenanme, 'w+t')
+        open(newunit=unit, file=filenanme)
+        call disp(r(1,1), header='Test_io_disp_real_scalar (brief) : ', brief=.true.)
+        call disp(r(1,1), unit=unit, header='Test_io_disp_real_scalar (brief) : ', brief=.true.)
+
+        call disp(r(1,:), header='Test_io_disp_real_vector (brief) : ', brief=.true.)
+        call disp(r(1,:), unit=unit, header='Test_io_disp_real_vector (brief) : ', brief=.true.)
+
+        call disp(r(:,1), header='Test_io_disp_real_vector : ', brief=.false.)
+        call disp(r(:,1), unit=unit, header='Test_io_disp_real_vector : ', brief=.false.)
+
+        call disp(r(1:2,1:2), header='Test_io_disp_real_matrix : ', brief=.false.)
+        call disp(r(1:2,1:2), unit=unit, header='Test_io_disp_real_matrix : ', brief=.false.)
+
+        call disp(r(:,:), header='Test_io_disp_real_matrix (brief) : ', brief=.true.)
+        call disp(r(:,:), unit=unit, header='Test_io_disp_real_matrix (brief) : ', brief=.true.)
+    
+        !! Checks
+        rewind(unit)
+        read(unit, '(A200)') string
+        call check_formatter(trim(adjustl(string)), 'Test_io_disp_real_scalar (brief) :', 'Header')
+        read(unit, '(A200)') string
+        call check_formatter(trim(adjustl(string)), '1.000', 'Value')
+        
+        read(unit, '(A200)') string
+        call check_formatter(trim(adjustl(string)), 'Test_io_disp_real_vector (brief) :', 'Header')
+        read(unit, '(A200)') string
+        call check_formatter(trim(adjustl(string)), '[vector size: 6]', 'Vector Info')
+        read(unit, '(A200)') string
+        call check_formatter(trim(adjustl(string)), &
+        '1.000        1.000        1.000              ...    1.000', 'Brief Vector')
+
+        read(unit, '(A200)') string
+        call check_formatter(trim(adjustl(string)), 'Test_io_disp_real_vector :', 'Header')
+        read(unit, '(A200)') string
+        call check_formatter(trim(adjustl(string)), '[vector size: 6]', 'Vector Info')
+        read(unit, '(A200)') string
+        call check_formatter(trim(adjustl(string)), &
+        '1.000        1.000        1.000        1.000        1.000        1.000', 'Brief Vector')
+
+        read(unit, '(A200)') string
+        call check_formatter(trim(adjustl(string)), 'Test_io_disp_real_matrix :', 'Header')
+        read(unit, '(A200)') string
+        call check_formatter(trim(adjustl(string)), '[matrix size: 2×2]', 'Matrix Info')
+        read(unit, '(A200)') string
+        call check_formatter(trim(adjustl(string)), &
+        '1.000        1.000', 'Matrix Vector 1')
+        read(unit, '(A200)') string
+        call check_formatter(trim(adjustl(string)), &
+        '1.000        1.000', 'Matrix Vector 2')
+
+        read(unit, '(A200)') string
+        call check_formatter(trim(adjustl(string)), 'Test_io_disp_real_matrix (brief) :', 'Header')
+        read(unit, '(A200)') string
+        call check_formatter(trim(adjustl(string)), '[matrix size: 6×6]', 'Matrix Info')
+        read(unit, '(A200)') string
+        call check_formatter(trim(adjustl(string)), &
+        '1.000        1.000        1.000              ...    1.000', 'Matrix Vector 1')
+        read(unit, '(A200)') string
+        call check_formatter(trim(adjustl(string)), &
+        '1.000        1.000        1.000              ...    1.000', 'Matrix Vector 2')
+        read(unit, '(A200)') string
+        call check_formatter(trim(adjustl(string)), &
+        '1.000        1.000        1.000              ...    1.000', 'Matrix Vector 3')
+        read(unit, '(A200)') string
+        call check_formatter(trim(adjustl(string)), &
+        ':            :            :            :            :', 'Matrix Vector ..')
+        read(unit, '(A200)') string
+        call check_formatter(trim(adjustl(string)), &
+        '1.000        1.000        1.000              ...    1.000', 'Matrix Vector Size(Matrix, 1)')
+        close(unit)
+
+    end subroutine test_io_disp_real
+
+    subroutine test_io_disp_integer
+
+        integer :: i(6,6) = 1
+        ! unit = open(filenanme, 'w+t')
+        open(newunit=unit, file=filenanme)
+        call disp(i(1,1), header='Test_io_disp_integer_scalar (brief) : ', brief=.true.)
+        call disp(i(1,1), unit=unit, header='Test_io_disp_integer_scalar (brief) : ', brief=.true.)
+
+        call disp(i(1,:), header='Test_io_disp_integer_vector (brief) : ', brief=.true.)
+        call disp(i(1,:), unit=unit, header='Test_io_disp_integer_vector (brief) : ', brief=.true.)
+
+        call disp(i(:,1), header='Test_io_disp_integer_vector : ', brief=.false.)
+        call disp(i(:,1), unit=unit, header='Test_io_disp_integer_vector : ', brief=.false.)
+
+        call disp(i(1:2,1:2), header='Test_io_disp_integer_matrix : ', brief=.false.)
+        call disp(i(1:2,1:2), unit=unit, header='Test_io_disp_integer_matrix : ', brief=.false.)
+
+        call disp(i(:,:), header='Test_io_disp_integer_matrix (brief) : ', brief=.true.)
+        call disp(i(:,:), unit=unit, header='Test_io_disp_integer_matrix (brief) : ', brief=.true.)
+    
+        !! Checks
+        rewind(unit)
+        read(unit, '(A200)') string
+        call check_formatter(trim(adjustl(string)), 'Test_io_disp_integer_scalar (brief) :', 'Header')
+        read(unit, '(A200)') string
+        call check_formatter(trim(adjustl(string)), '1', 'Value')
+        
+        read(unit, '(A200)') string
+        call check_formatter(trim(adjustl(string)), 'Test_io_disp_integer_vector (brief) :', 'Header')
+        read(unit, '(A200)') string
+        call check_formatter(trim(adjustl(string)), '[vector size: 6]', 'Vector Info')
+        read(unit, '(A200)') string
+        call check_formatter(trim(adjustl(string)), &
+        '1            1            1          ...            1', 'Brief Vector')
+
+        read(unit, '(A200)') string
+        call check_formatter(trim(adjustl(string)), 'Test_io_disp_integer_vector :', 'Header')
+        read(unit, '(A200)') string
+        call check_formatter(trim(adjustl(string)), '[vector size: 6]', 'Vector Info')
+        read(unit, '(A200)') string
+        call check_formatter(trim(adjustl(string)), &
+        '1            1            1            1            1            1', 'Brief Vector')
+
+        read(unit, '(A200)') string
+        call check_formatter(trim(adjustl(string)), 'Test_io_disp_integer_matrix :', 'Header')
+        read(unit, '(A200)') string
+        call check_formatter(trim(adjustl(string)), '[matrix size: 2×2]', 'Matrix Info')
+        read(unit, '(A200)') string
+        call check_formatter(trim(adjustl(string)), &
+        '1            1', 'Matrix Vector 1')
+        read(unit, '(A200)') string
+        call check_formatter(trim(adjustl(string)), &
+        '1            1', 'Matrix Vector 2')
+
+        read(unit, '(A200)') string
+        call check_formatter(trim(adjustl(string)), 'Test_io_disp_integer_matrix (brief) :', 'Header')
+        read(unit, '(A200)') string
+        call check_formatter(trim(adjustl(string)), '[matrix size: 6×6]', 'Matrix Info')
+        read(unit, '(A200)') string
+        call check_formatter(trim(adjustl(string)), &
+        '1            1            1          ...            1', 'Matrix Vector 1')
+        read(unit, '(A200)') string
+        call check_formatter(trim(adjustl(string)), &
+        '1            1            1          ...            1', 'Matrix Vector 2')
+        read(unit, '(A200)') string
+        call check_formatter(trim(adjustl(string)), &
+        '1            1            1          ...            1', 'Matrix Vector 3')
+        read(unit, '(A200)') string
+        call check_formatter(trim(adjustl(string)), &
+        ':            :            :            :            :', 'Matrix Vector ..')
+        read(unit, '(A200)') string
+        call check_formatter(trim(adjustl(string)), &
+        '1            1            1          ...            1', 'Matrix Vector Size(Matrix, 1)')
+        close(unit)
+
+    end subroutine test_io_disp_integer
+
+    subroutine test_io_disp_logical
+
+        logical :: l(6,6) = .true.
+        ! unit = open(filenanme, 'w+t')
+        open(newunit=unit, file=filenanme)
+        call disp(l(1,1), header='Test_io_disp_logical_scalar (brief) : ', brief=.true.)
+        call disp(l(1,1), unit=unit, header='Test_io_disp_logical_scalar (brief) : ', brief=.true.)
+
+        call disp(l(1,:), header='Test_io_disp_logical_vector (brief) : ', brief=.true.)
+        call disp(l(1,:), unit=unit, header='Test_io_disp_logical_vector (brief) : ', brief=.true.)
+
+        call disp(l(:,1), header='Test_io_disp_logical_vector : ', brief=.false.)
+        call disp(l(:,1), unit=unit, header='Test_io_disp_logical_vector : ', brief=.false.)
+
+        call disp(l(1:2,1:2), header='Test_io_disp_logical_matrix : ', brief=.false.)
+        call disp(l(1:2,1:2), unit=unit, header='Test_io_disp_logical_matrix : ', brief=.false.)
+
+        call disp(l(:,:), header='Test_io_disp_logical_matrix (brief) : ', brief=.true.)
+        call disp(l(:,:), unit=unit, header='Test_io_disp_logical_matrix (brief) : ', brief=.true.)
+    
+        !! Checks
+        rewind(unit)
+        read(unit, '(A200)') string
+        call check_formatter(trim(adjustl(string)), 'Test_io_disp_logical_scalar (brief) :', 'Header')
+        read(unit, '(A200)') string
+        call check_formatter(trim(adjustl(string)), 'T', 'Value')
+        
+        read(unit, '(A200)') string
+        call check_formatter(trim(adjustl(string)), 'Test_io_disp_logical_vector (brief) :', 'Header')
+        read(unit, '(A200)') string
+        call check_formatter(trim(adjustl(string)), '[vector size: 6]', 'Vector Info')
+        read(unit, '(A200)') string
+        call check_formatter(trim(adjustl(string)), &
+        'T            T            T          ...            T', 'Brief Vector')
+
+        read(unit, '(A200)') string
+        call check_formatter(trim(adjustl(string)), 'Test_io_disp_logical_vector :', 'Header')
+        read(unit, '(A200)') string
+        call check_formatter(trim(adjustl(string)), '[vector size: 6]', 'Vector Info')
+        read(unit, '(A200)') string
+        call check_formatter(trim(adjustl(string)), &
+        'T            T            T            T            T            T', 'Brief Vector')
+
+        read(unit, '(A200)') string
+        call check_formatter(trim(adjustl(string)), 'Test_io_disp_logical_matrix :', 'Header')
+        read(unit, '(A200)') string
+        call check_formatter(trim(adjustl(string)), '[matrix size: 2×2]', 'Matrix Info')
+        read(unit, '(A200)') string
+        call check_formatter(trim(adjustl(string)), &
+        'T            T', 'Matrix Vector 1')
+        read(unit, '(A200)') string
+        call check_formatter(trim(adjustl(string)), &
+        'T            T', 'Matrix Vector 2')
+
+        read(unit, '(A200)') string
+        call check_formatter(trim(adjustl(string)), 'Test_io_disp_logical_matrix (brief) :', 'Header')
+        read(unit, '(A200)') string
+        call check_formatter(trim(adjustl(string)), '[matrix size: 6×6]', 'Matrix Info')
+        read(unit, '(A200)') string
+        call check_formatter(trim(adjustl(string)), &
+        'T            T            T          ...            T', 'Matrix Vector 1')
+        read(unit, '(A200)') string
+        call check_formatter(trim(adjustl(string)), &
+        'T            T            T          ...            T', 'Matrix Vector 2')
+        read(unit, '(A200)') string
+        call check_formatter(trim(adjustl(string)), &
+        'T            T            T          ...            T', 'Matrix Vector 3')
+        read(unit, '(A200)') string
+        call check_formatter(trim(adjustl(string)), &
+        ':            :            :            :            :', 'Matrix Vector ..')
+        read(unit, '(A200)') string
+        call check_formatter(trim(adjustl(string)), &
+        'T            T            T          ...            T', 'Matrix Vector Size(Matrix, 1)')
+        close(unit)
+
+    end subroutine test_io_disp_logical
+
+    subroutine test_io_disp_string
+
+        character(*), parameter :: str = 'It is a string.'
+        ! unit = open(filenanme, 'w+t')
+        open(newunit=unit, file=filenanme)
+        call disp(str, header='Test_io_disp_string_scalar (brief) : ', brief=.true.)
+        call disp(str, unit=unit, header='Test_io_disp_string_scalar (brief) : ', brief=.true.)
+    
+        !! Checks
+        rewind(unit)
+        read(unit, '(A200)') string
+        call check_formatter(trim(adjustl(string)), 'Test_io_disp_string_scalar (brief) :', 'Header')
+        read(unit, '(A200)') string
+        call check_formatter(trim(adjustl(string)), 'It is a string.', 'Value')
+        close(unit)
+
+    end subroutine test_io_disp_string
+
+end module test_io_disp
+
+program tester
+    use test_io_disp
+    call test_io_disp_complex
+    call test_io_disp_real
+    call test_io_disp_integer
+    call test_io_disp_logical
+    call test_io_disp_string
+end program tester

From 4e94891b758a95abe7a57e076e725860533c4988 Mon Sep 17 00:00:00 2001
From: zoziha13 <1325686572@qq.com>
Date: Mon, 12 Jul 2021 00:10:59 +0800
Subject: [PATCH 07/14] Correct spelling errors

---
 doc/specs/stdlib_io.md | 4 ++--
 src/stdlib_io.fypp     | 2 +-
 2 files changed, 3 insertions(+), 3 deletions(-)

diff --git a/doc/specs/stdlib_io.md b/doc/specs/stdlib_io.md
index 4bea7d810..8ecf49c3e 100644
--- a/doc/specs/stdlib_io.md
+++ b/doc/specs/stdlib_io.md
@@ -168,13 +168,13 @@ For null:
 `header`: Shall be a scalar of type `character` with any length (usually used to comment data information).
     This is an `intent(in)` and `optional` argument.
 
-`brief`: Shall be an `logical` scalar, controling an abridged version of the `value` object is printed.
+`brief`: Shall be an `logical` scalar, controlling an abridged version of the `value` object is printed.
     This is an `intent(in)` and `optional` argument.
 
 ### Output
 
 The result is to print `header` and `value` on the screen (or another output unit) in this order.  
-If `value` is a `array` type, the dimension length information of the `array` will also be outputed.
+If `value` is a `array` type, the dimension length information of the `array` will also be outputted.
 
 ### Example
 
diff --git a/src/stdlib_io.fypp b/src/stdlib_io.fypp
index e94fdcc48..a3a38bb59 100644
--- a/src/stdlib_io.fypp
+++ b/src/stdlib_io.fypp
@@ -23,7 +23,7 @@ module stdlib_io
     !! version: experimental
     !!
     !! Display any type of scalar, vector and matrix.
-    !! ([Specification](../page/specs/stdlib_io.html))
+    !! ([Specification](../page/specs/stdlib_io.html#disp-display-your-data-to-the-screen-or-another-output-unit))
     #:set DISP_KINDS_TYPES = REAL_KINDS_TYPES + INT_KINDS_TYPES &
         & + CMPLX_KINDS_TYPES + LOG_KINDS_TYPES
     #:set DISP_RANKS = range(0, 3)

From 328ea755155bff5848fdb0e67345cb437035d776 Mon Sep 17 00:00:00 2001
From: zoziha13 <1325686572@qq.com>
Date: Mon, 12 Jul 2021 00:11:48 +0800
Subject: [PATCH 08/14] Add a valid `test_io_disp.f90`

---
 doc/specs/stdlib_io.md        |  18 +-
 src/stdlib_io_disp.fypp       |  27 +--
 src/tests/io/test_io_disp.f90 | 404 +++++++++++++++++++++++++++++++---
 3 files changed, 402 insertions(+), 47 deletions(-)

diff --git a/doc/specs/stdlib_io.md b/doc/specs/stdlib_io.md
index e1c61fd18..4bea7d810 100644
--- a/doc/specs/stdlib_io.md
+++ b/doc/specs/stdlib_io.md
@@ -143,7 +143,7 @@ Display any type of scalar, vector or matrix.
 
 Make good use of similar to the following usage, can help you understand the data information in the `array`.
 ```fortran
-call disp( A(i, j, 2, :, :) [, unit, header, brief] )    !! `i, j, ...` can be determined by `do` loop.
+call disp( A(i, j, 2, :, 1:10) [, unit, header, brief] )    !! `i, j, ...` can be determined by `do` loop.
 ```
 
 Generally, except for `complex` type, any other type of scalar or single element of the `array` will be printed out with a width of 12 characters and a space separator.  
@@ -174,7 +174,7 @@ For null:
 ### Output
 
 The result is to print `header` and `value` on the screen (or another output unit) in this order.  
-If `value` is a `array` type, the dimension length information of the `array` will also be output.
+If `value` is a `array` type, the dimension length information of the `array` will also be outputed.
 
 ### Example
 
@@ -199,18 +199,19 @@ program test_io_disp
     call disp()
 
     call disp(r, header='disp(r):')
+    call disp(r(1,:), header='disp(r(1,:))')
     call disp(c, header='disp(c):')
     call disp(i, header='disp(i):')
     call disp(l, header='disp(l):', brief=.true.)
 
-    call disp(c_3d(:,:,3), header='disp(c_3d, 3):', brief=.true.)
-    call disp(c_3d(2,:,:), header='disp(c_3d, 2):', brief=.true.)
+    call disp(c_3d(:,:,3), header='disp(c_3d(:,:,3)):', brief=.true.)
+    call disp(c_3d(2,:,:), header='disp(c_3d(2,:,:)):', brief=.true.)
 
 end program test_io_disp
 ```
 **Result:**
 ```fortran
-disp(string):
+ disp(string):
  string
  It is a note.
 
@@ -218,6 +219,9 @@ disp(string):
  [matrix size: 2×3]
  -0.1000E-10  -0.1000E+11    1.000
    1.000        1.000        1.000
+ disp(r(1,:))
+ [vector size: 3]
+ -0.1000E-10  -0.1000E+11    1.000
  disp(c):
  [matrix size: 2×3]
             (1.000,0.000)             (1.000,0.000)             (1.000,0.000)
@@ -233,11 +237,11 @@ disp(string):
            T            T            T          ...            T
            :            :            :            :            :
            T            T            T          ...            T
- disp(c_3d, 3):
+ disp(c_3d(:,:,3)):
  [matrix size: 2×100]
             (2.000,0.000)             (2.000,0.000)             (2.000,0.000)                       ...             (2.000,0.000)  
             (2.000,0.000)             (2.000,0.000)             (2.000,0.000)                       ...             (2.000,0.000)  
- disp(c_3d, 2):
+ disp(c_3d(2,:,:)):
  [matrix size: 100×20]
             (2.000,0.000)             (2.000,0.000)             (2.000,0.000)                       ...             (2.000,0.000)  
             (2.000,0.000)             (2.000,0.000)             (2.000,0.000)                       ...             (2.000,0.000)  
diff --git a/src/stdlib_io_disp.fypp b/src/stdlib_io_disp.fypp
index 027d29677..e6ccf3871 100644
--- a/src/stdlib_io_disp.fypp
+++ b/src/stdlib_io_disp.fypp
@@ -9,6 +9,7 @@ submodule (stdlib_io) stdlib_io_disp
     implicit none
     character(len=*), parameter :: fmt_r = '(*(g12.4, 1x))'
     character(len=*), parameter :: fmt_c = '(*(g25.0, 1x))'
+    character(len=*), parameter :: format_ = '(g0.4)'
     
 contains
     
@@ -83,7 +84,7 @@ contains
         integer :: unit_
         unit_  = merge(unit, output_unit, present(unit))
         if(present(header)) write(unit_, *) header
-        write(unit_, fmt_c) format_to_string(value, '(g0.4)')
+        write(unit_, fmt_c) format_to_string(value, format_)
     end procedure disp_0_${type[0]}$${kind}$
 
     module procedure disp_1_${type[0]}$${kind}$
@@ -97,10 +98,10 @@ contains
         if(present(header)) write(unit_, *) header
         write(unit_, *) '[vector size: '//to_string(m)//']'
         if(brief_ .and. m > 5) then
-            write(unit_, fmt_c) (format_to_string(value(i), '(g0.4)'), i=1, 3), &
-                          '...', format_to_string(value(m), '(g0.4)')
+            write(unit_, fmt_c) (format_to_string(value(i), format_), i=1, 3), &
+                          '...', format_to_string(value(m), format_)
         else
-            write(unit_, fmt_c) (format_to_string(value(i), '(g0.4)'), i=1, m)
+            write(unit_, fmt_c) (format_to_string(value(i), format_), i=1, m)
         end if
     end procedure disp_1_${type[0]}$${kind}$
 
@@ -119,28 +120,28 @@ contains
         if(brief_ .and. (m > 5 .or. n > 5)) then
             if(m > 5 .and. n > 5) then
                 do i = 1, 3
-                    write(unit_, fmt_c) (format_to_string(value(i,j), '(g0.4)'), j=1, 3), &
-                                  '...', format_to_string(value(i,n), '(g0.4)')
+                    write(unit_, fmt_c) (format_to_string(value(i,j), format_), j=1, 3), &
+                                  '...', format_to_string(value(i,n), format_)
                 end do
                 write(unit_, fmt_c) ':', ':', ':', ':', ':'
-                write(unit_, fmt_c) (format_to_string(value(m,j), '(g0.4)'), j=1, 3), &
-                              '...', format_to_string(value(m,n), '(g0.4)')
+                write(unit_, fmt_c) (format_to_string(value(m,j), format_), j=1, 3), &
+                              '...', format_to_string(value(m,n), format_)
             elseif(m > 5 .and. n <= 5) then
                 do i = 1, 3
-                    write(unit_, fmt_c) (format_to_string(value(i,j), '(g0.4)'), j=1, n)
+                    write(unit_, fmt_c) (format_to_string(value(i,j), format_), j=1, n)
                 end do
                 colon(1:n) = ':'
                 write(unit_, fmt_c) colon(1:n)
-                write(unit_, fmt_c) (format_to_string(value(m,j), '(g0.4)'), j=1, n)
+                write(unit_, fmt_c) (format_to_string(value(m,j), format_), j=1, n)
             elseif(m <= 5 .and. n > 5) then
                 do i = 1, m
-                    write(unit_, fmt_c) (format_to_string(value(m,j), '(g0.4)'), j=1, 3), &
-                                  '...', format_to_string(value(m,n), '(g0.4)')
+                    write(unit_, fmt_c) (format_to_string(value(m,j), format_), j=1, 3), &
+                                  '...', format_to_string(value(m,n), format_)
                 end do
             end if
         else
             do i = 1, m
-                write(unit_, fmt_c) (format_to_string(value(i,j), '(g0.4)'), j=1, n)
+                write(unit_, fmt_c) (format_to_string(value(i,j), format_), j=1, n)
             end do
         end if
     end procedure disp_2_${type[0]}$${kind}$
diff --git a/src/tests/io/test_io_disp.f90 b/src/tests/io/test_io_disp.f90
index c17284fc6..c65be16dd 100644
--- a/src/tests/io/test_io_disp.f90
+++ b/src/tests/io/test_io_disp.f90
@@ -1,28 +1,378 @@
-program test_io_disp
-    
-    use :: stdlib_io, only: disp
+module test_io_disp
+
+    use stdlib_strings, only: starts_with
+    use stdlib_error, only: check
+    use stdlib_io, only: disp, open
     implicit none
-    real(8) :: r(2, 3)
-    complex :: c(2, 3), c_3d(2, 100, 20)
-    integer :: i(2, 3)
-    logical :: l(10, 10)
-
-    r = 1.; c = 1.; c_3d = 2.; i = 1; l = .true.
-    r(1, 1) = -1.e-11
-    r(1, 2) = -1.e10
-    c(2, 2) = (-1.e10,-1.e10)
-    c_3d(1,3,1) = (1000, 0.001)
-    c_3d(1,3,2) = (1.e4, 100.)
-    call disp('string', header='disp(string):')
-    call disp('It is a note.')
-    call disp()
-
-    call disp(r, header='disp(r):')
-    call disp(c, header='disp(c):')
-    call disp(i, header='disp(i):')
-    call disp(l, header='disp(l):', brief=.true.)
-
-    call disp(c_3d(:,:,3), header='disp(c_3d, 3):', brief=.true.)
-    call disp(c_3d(2,:,:), header='disp(c_3d, 2):', brief=.true.)
-
-end program test_io_disp
\ No newline at end of file
+
+    integer :: unit
+    character(*), parameter :: filenanme = "./test_io_disp.tmp"
+    character(len=512) :: string
+
+contains
+
+    subroutine check_formatter(actual, expected, description, partial)
+        character(len=*), intent(in) :: actual, expected, description
+        logical, intent(in), optional :: partial
+        logical :: stat
+        character(len=:), allocatable :: msg
+
+        if (merge(partial, .false., present(partial))) then
+            stat = starts_with(actual, expected)
+        else
+            stat = actual == expected
+        end if
+
+        if (.not. stat) then
+            msg = description//new_line("a")// &
+                & "Expected: '"//expected//"' but got '"//actual//"'"
+        else
+            print '(" - ", a, /, "   Result: ''", a, "''")', description, actual
+        end if
+
+        call check(stat, msg)
+
+    end subroutine check_formatter
+
+    subroutine test_io_disp_complex
+        complex :: c(6,6) = (1.0, 1.0)
+        ! unit = open(filenanme, 'w+t')
+        open(newunit=unit, file=filenanme)
+        call disp(c(1,1), header='Test_io_disp_complex_scalar (brief) : ', brief=.true.)
+        call disp(c(1,1), unit=unit, header='Test_io_disp_complex_scalar (brief) : ', brief=.true.)
+
+        call disp(c(1,:), header='Test_io_disp_complex_vector (brief) : ', brief=.true.)
+        call disp(c(1,:), unit=unit, header='Test_io_disp_complex_vector (brief) : ', brief=.true.)
+
+        call disp(c(:,1), header='Test_io_disp_complex_vector : ', brief=.false.)
+        call disp(c(:,1), unit=unit, header='Test_io_disp_complex_vector : ', brief=.false.)
+
+        call disp(c(1:2,1:2), header='Test_io_disp_complex_matrix : ', brief=.false.)
+        call disp(c(1:2,1:2), unit=unit, header='Test_io_disp_complex_matrix : ', brief=.false.)
+
+        call disp(c(:,:), header='Test_io_disp_complex_matrix (brief) : ', brief=.true.)
+        call disp(c(:,:), unit=unit, header='Test_io_disp_complex_matrix (brief) : ', brief=.true.)
+    
+        !! Checks
+        rewind(unit)
+        read(unit, '(A200)') string
+        call check_formatter(trim(adjustl(string)), 'Test_io_disp_complex_scalar (brief) :', 'Header')
+        read(unit, '(A200)') string
+        call check_formatter(trim(adjustl(string)), '(1.000,1.000)', 'Value')
+        
+        read(unit, '(A200)') string
+        call check_formatter(trim(adjustl(string)), 'Test_io_disp_complex_vector (brief) :', 'Header')
+        read(unit, '(A200)') string
+        call check_formatter(trim(adjustl(string)), '[vector size: 6]', 'Vector Info')
+        read(unit, '(A200)') string
+        call check_formatter(trim(adjustl(string)), &
+        '(1.000,1.000)             (1.000,1.000)             (1.000,1.000)  &
+        &                     ...             (1.000,1.000)', 'Brief Vector')
+
+        read(unit, '(A200)') string
+        call check_formatter(trim(adjustl(string)), 'Test_io_disp_complex_vector :', 'Header')
+        read(unit, '(A200)') string
+        call check_formatter(trim(adjustl(string)), '[vector size: 6]', 'Vector Info')
+        read(unit, '(A200)') string
+        call check_formatter(trim(adjustl(string)), &
+        '(1.000,1.000)             (1.000,1.000)             (1.000,1.000)    &
+        &         (1.000,1.000)             (1.000,1.000)             (1.000,1.000)', 'Brief Vector')
+
+        read(unit, '(A200)') string
+        call check_formatter(trim(adjustl(string)), 'Test_io_disp_complex_matrix :', 'Header')
+        read(unit, '(A200)') string
+        call check_formatter(trim(adjustl(string)), '[matrix size: 2×2]', 'Matrix Info')
+        read(unit, '(A200)') string
+        call check_formatter(trim(adjustl(string)), &
+        '(1.000,1.000)             (1.000,1.000)', 'Matrix Vector 1')
+        read(unit, '(A200)') string
+        call check_formatter(trim(adjustl(string)), &
+        '(1.000,1.000)             (1.000,1.000)', 'Matrix Vector 2')
+
+        read(unit, '(A200)') string
+        call check_formatter(trim(adjustl(string)), 'Test_io_disp_complex_matrix (brief) :', 'Header')
+        read(unit, '(A200)') string
+        call check_formatter(trim(adjustl(string)), '[matrix size: 6×6]', 'Matrix Info')
+        read(unit, '(A200)') string
+        call check_formatter(trim(adjustl(string)), &
+        '(1.000,1.000)             (1.000,1.000)             (1.000,1.000)    &
+        &                   ...             (1.000,1.000)', 'Matrix Vector 1')
+        read(unit, '(A200)') string
+        call check_formatter(trim(adjustl(string)), &
+        '(1.000,1.000)             (1.000,1.000)             (1.000,1.000)    &
+        &                   ...             (1.000,1.000)', 'Matrix Vector 2')
+        read(unit, '(A200)') string
+        call check_formatter(trim(adjustl(string)), &
+        '(1.000,1.000)             (1.000,1.000)             (1.000,1.000)    &
+        &                   ...             (1.000,1.000)', 'Matrix Vector 3')
+        read(unit, '(A200)') string
+        call check_formatter(trim(adjustl(string)), &
+        ':                         :                         :                &
+        &         :                         :', 'Matrix Vector ..')
+        read(unit, '(A200)') string
+        call check_formatter(trim(adjustl(string)), &
+        '(1.000,1.000)             (1.000,1.000)             (1.000,1.000)    &
+        &                   ...             (1.000,1.000)', 'Matrix Vector Size(Matrix, 1)')
+        close(unit)
+
+    end subroutine test_io_disp_complex
+
+    subroutine test_io_disp_real
+
+        real :: r(6,6) = 1.0
+        ! unit = open(filenanme, 'w+t')
+        open(newunit=unit, file=filenanme)
+        call disp(r(1,1), header='Test_io_disp_real_scalar (brief) : ', brief=.true.)
+        call disp(r(1,1), unit=unit, header='Test_io_disp_real_scalar (brief) : ', brief=.true.)
+
+        call disp(r(1,:), header='Test_io_disp_real_vector (brief) : ', brief=.true.)
+        call disp(r(1,:), unit=unit, header='Test_io_disp_real_vector (brief) : ', brief=.true.)
+
+        call disp(r(:,1), header='Test_io_disp_real_vector : ', brief=.false.)
+        call disp(r(:,1), unit=unit, header='Test_io_disp_real_vector : ', brief=.false.)
+
+        call disp(r(1:2,1:2), header='Test_io_disp_real_matrix : ', brief=.false.)
+        call disp(r(1:2,1:2), unit=unit, header='Test_io_disp_real_matrix : ', brief=.false.)
+
+        call disp(r(:,:), header='Test_io_disp_real_matrix (brief) : ', brief=.true.)
+        call disp(r(:,:), unit=unit, header='Test_io_disp_real_matrix (brief) : ', brief=.true.)
+    
+        !! Checks
+        rewind(unit)
+        read(unit, '(A200)') string
+        call check_formatter(trim(adjustl(string)), 'Test_io_disp_real_scalar (brief) :', 'Header')
+        read(unit, '(A200)') string
+        call check_formatter(trim(adjustl(string)), '1.000', 'Value')
+        
+        read(unit, '(A200)') string
+        call check_formatter(trim(adjustl(string)), 'Test_io_disp_real_vector (brief) :', 'Header')
+        read(unit, '(A200)') string
+        call check_formatter(trim(adjustl(string)), '[vector size: 6]', 'Vector Info')
+        read(unit, '(A200)') string
+        call check_formatter(trim(adjustl(string)), &
+        '1.000        1.000        1.000              ...    1.000', 'Brief Vector')
+
+        read(unit, '(A200)') string
+        call check_formatter(trim(adjustl(string)), 'Test_io_disp_real_vector :', 'Header')
+        read(unit, '(A200)') string
+        call check_formatter(trim(adjustl(string)), '[vector size: 6]', 'Vector Info')
+        read(unit, '(A200)') string
+        call check_formatter(trim(adjustl(string)), &
+        '1.000        1.000        1.000        1.000        1.000        1.000', 'Brief Vector')
+
+        read(unit, '(A200)') string
+        call check_formatter(trim(adjustl(string)), 'Test_io_disp_real_matrix :', 'Header')
+        read(unit, '(A200)') string
+        call check_formatter(trim(adjustl(string)), '[matrix size: 2×2]', 'Matrix Info')
+        read(unit, '(A200)') string
+        call check_formatter(trim(adjustl(string)), &
+        '1.000        1.000', 'Matrix Vector 1')
+        read(unit, '(A200)') string
+        call check_formatter(trim(adjustl(string)), &
+        '1.000        1.000', 'Matrix Vector 2')
+
+        read(unit, '(A200)') string
+        call check_formatter(trim(adjustl(string)), 'Test_io_disp_real_matrix (brief) :', 'Header')
+        read(unit, '(A200)') string
+        call check_formatter(trim(adjustl(string)), '[matrix size: 6×6]', 'Matrix Info')
+        read(unit, '(A200)') string
+        call check_formatter(trim(adjustl(string)), &
+        '1.000        1.000        1.000              ...    1.000', 'Matrix Vector 1')
+        read(unit, '(A200)') string
+        call check_formatter(trim(adjustl(string)), &
+        '1.000        1.000        1.000              ...    1.000', 'Matrix Vector 2')
+        read(unit, '(A200)') string
+        call check_formatter(trim(adjustl(string)), &
+        '1.000        1.000        1.000              ...    1.000', 'Matrix Vector 3')
+        read(unit, '(A200)') string
+        call check_formatter(trim(adjustl(string)), &
+        ':            :            :            :            :', 'Matrix Vector ..')
+        read(unit, '(A200)') string
+        call check_formatter(trim(adjustl(string)), &
+        '1.000        1.000        1.000              ...    1.000', 'Matrix Vector Size(Matrix, 1)')
+        close(unit)
+
+    end subroutine test_io_disp_real
+
+    subroutine test_io_disp_integer
+
+        integer :: i(6,6) = 1
+        ! unit = open(filenanme, 'w+t')
+        open(newunit=unit, file=filenanme)
+        call disp(i(1,1), header='Test_io_disp_integer_scalar (brief) : ', brief=.true.)
+        call disp(i(1,1), unit=unit, header='Test_io_disp_integer_scalar (brief) : ', brief=.true.)
+
+        call disp(i(1,:), header='Test_io_disp_integer_vector (brief) : ', brief=.true.)
+        call disp(i(1,:), unit=unit, header='Test_io_disp_integer_vector (brief) : ', brief=.true.)
+
+        call disp(i(:,1), header='Test_io_disp_integer_vector : ', brief=.false.)
+        call disp(i(:,1), unit=unit, header='Test_io_disp_integer_vector : ', brief=.false.)
+
+        call disp(i(1:2,1:2), header='Test_io_disp_integer_matrix : ', brief=.false.)
+        call disp(i(1:2,1:2), unit=unit, header='Test_io_disp_integer_matrix : ', brief=.false.)
+
+        call disp(i(:,:), header='Test_io_disp_integer_matrix (brief) : ', brief=.true.)
+        call disp(i(:,:), unit=unit, header='Test_io_disp_integer_matrix (brief) : ', brief=.true.)
+    
+        !! Checks
+        rewind(unit)
+        read(unit, '(A200)') string
+        call check_formatter(trim(adjustl(string)), 'Test_io_disp_integer_scalar (brief) :', 'Header')
+        read(unit, '(A200)') string
+        call check_formatter(trim(adjustl(string)), '1', 'Value')
+        
+        read(unit, '(A200)') string
+        call check_formatter(trim(adjustl(string)), 'Test_io_disp_integer_vector (brief) :', 'Header')
+        read(unit, '(A200)') string
+        call check_formatter(trim(adjustl(string)), '[vector size: 6]', 'Vector Info')
+        read(unit, '(A200)') string
+        call check_formatter(trim(adjustl(string)), &
+        '1            1            1          ...            1', 'Brief Vector')
+
+        read(unit, '(A200)') string
+        call check_formatter(trim(adjustl(string)), 'Test_io_disp_integer_vector :', 'Header')
+        read(unit, '(A200)') string
+        call check_formatter(trim(adjustl(string)), '[vector size: 6]', 'Vector Info')
+        read(unit, '(A200)') string
+        call check_formatter(trim(adjustl(string)), &
+        '1            1            1            1            1            1', 'Brief Vector')
+
+        read(unit, '(A200)') string
+        call check_formatter(trim(adjustl(string)), 'Test_io_disp_integer_matrix :', 'Header')
+        read(unit, '(A200)') string
+        call check_formatter(trim(adjustl(string)), '[matrix size: 2×2]', 'Matrix Info')
+        read(unit, '(A200)') string
+        call check_formatter(trim(adjustl(string)), &
+        '1            1', 'Matrix Vector 1')
+        read(unit, '(A200)') string
+        call check_formatter(trim(adjustl(string)), &
+        '1            1', 'Matrix Vector 2')
+
+        read(unit, '(A200)') string
+        call check_formatter(trim(adjustl(string)), 'Test_io_disp_integer_matrix (brief) :', 'Header')
+        read(unit, '(A200)') string
+        call check_formatter(trim(adjustl(string)), '[matrix size: 6×6]', 'Matrix Info')
+        read(unit, '(A200)') string
+        call check_formatter(trim(adjustl(string)), &
+        '1            1            1          ...            1', 'Matrix Vector 1')
+        read(unit, '(A200)') string
+        call check_formatter(trim(adjustl(string)), &
+        '1            1            1          ...            1', 'Matrix Vector 2')
+        read(unit, '(A200)') string
+        call check_formatter(trim(adjustl(string)), &
+        '1            1            1          ...            1', 'Matrix Vector 3')
+        read(unit, '(A200)') string
+        call check_formatter(trim(adjustl(string)), &
+        ':            :            :            :            :', 'Matrix Vector ..')
+        read(unit, '(A200)') string
+        call check_formatter(trim(adjustl(string)), &
+        '1            1            1          ...            1', 'Matrix Vector Size(Matrix, 1)')
+        close(unit)
+
+    end subroutine test_io_disp_integer
+
+    subroutine test_io_disp_logical
+
+        logical :: l(6,6) = .true.
+        ! unit = open(filenanme, 'w+t')
+        open(newunit=unit, file=filenanme)
+        call disp(l(1,1), header='Test_io_disp_logical_scalar (brief) : ', brief=.true.)
+        call disp(l(1,1), unit=unit, header='Test_io_disp_logical_scalar (brief) : ', brief=.true.)
+
+        call disp(l(1,:), header='Test_io_disp_logical_vector (brief) : ', brief=.true.)
+        call disp(l(1,:), unit=unit, header='Test_io_disp_logical_vector (brief) : ', brief=.true.)
+
+        call disp(l(:,1), header='Test_io_disp_logical_vector : ', brief=.false.)
+        call disp(l(:,1), unit=unit, header='Test_io_disp_logical_vector : ', brief=.false.)
+
+        call disp(l(1:2,1:2), header='Test_io_disp_logical_matrix : ', brief=.false.)
+        call disp(l(1:2,1:2), unit=unit, header='Test_io_disp_logical_matrix : ', brief=.false.)
+
+        call disp(l(:,:), header='Test_io_disp_logical_matrix (brief) : ', brief=.true.)
+        call disp(l(:,:), unit=unit, header='Test_io_disp_logical_matrix (brief) : ', brief=.true.)
+    
+        !! Checks
+        rewind(unit)
+        read(unit, '(A200)') string
+        call check_formatter(trim(adjustl(string)), 'Test_io_disp_logical_scalar (brief) :', 'Header')
+        read(unit, '(A200)') string
+        call check_formatter(trim(adjustl(string)), 'T', 'Value')
+        
+        read(unit, '(A200)') string
+        call check_formatter(trim(adjustl(string)), 'Test_io_disp_logical_vector (brief) :', 'Header')
+        read(unit, '(A200)') string
+        call check_formatter(trim(adjustl(string)), '[vector size: 6]', 'Vector Info')
+        read(unit, '(A200)') string
+        call check_formatter(trim(adjustl(string)), &
+        'T            T            T          ...            T', 'Brief Vector')
+
+        read(unit, '(A200)') string
+        call check_formatter(trim(adjustl(string)), 'Test_io_disp_logical_vector :', 'Header')
+        read(unit, '(A200)') string
+        call check_formatter(trim(adjustl(string)), '[vector size: 6]', 'Vector Info')
+        read(unit, '(A200)') string
+        call check_formatter(trim(adjustl(string)), &
+        'T            T            T            T            T            T', 'Brief Vector')
+
+        read(unit, '(A200)') string
+        call check_formatter(trim(adjustl(string)), 'Test_io_disp_logical_matrix :', 'Header')
+        read(unit, '(A200)') string
+        call check_formatter(trim(adjustl(string)), '[matrix size: 2×2]', 'Matrix Info')
+        read(unit, '(A200)') string
+        call check_formatter(trim(adjustl(string)), &
+        'T            T', 'Matrix Vector 1')
+        read(unit, '(A200)') string
+        call check_formatter(trim(adjustl(string)), &
+        'T            T', 'Matrix Vector 2')
+
+        read(unit, '(A200)') string
+        call check_formatter(trim(adjustl(string)), 'Test_io_disp_logical_matrix (brief) :', 'Header')
+        read(unit, '(A200)') string
+        call check_formatter(trim(adjustl(string)), '[matrix size: 6×6]', 'Matrix Info')
+        read(unit, '(A200)') string
+        call check_formatter(trim(adjustl(string)), &
+        'T            T            T          ...            T', 'Matrix Vector 1')
+        read(unit, '(A200)') string
+        call check_formatter(trim(adjustl(string)), &
+        'T            T            T          ...            T', 'Matrix Vector 2')
+        read(unit, '(A200)') string
+        call check_formatter(trim(adjustl(string)), &
+        'T            T            T          ...            T', 'Matrix Vector 3')
+        read(unit, '(A200)') string
+        call check_formatter(trim(adjustl(string)), &
+        ':            :            :            :            :', 'Matrix Vector ..')
+        read(unit, '(A200)') string
+        call check_formatter(trim(adjustl(string)), &
+        'T            T            T          ...            T', 'Matrix Vector Size(Matrix, 1)')
+        close(unit)
+
+    end subroutine test_io_disp_logical
+
+    subroutine test_io_disp_string
+
+        character(*), parameter :: str = 'It is a string.'
+        ! unit = open(filenanme, 'w+t')
+        open(newunit=unit, file=filenanme)
+        call disp(str, header='Test_io_disp_string_scalar (brief) : ', brief=.true.)
+        call disp(str, unit=unit, header='Test_io_disp_string_scalar (brief) : ', brief=.true.)
+    
+        !! Checks
+        rewind(unit)
+        read(unit, '(A200)') string
+        call check_formatter(trim(adjustl(string)), 'Test_io_disp_string_scalar (brief) :', 'Header')
+        read(unit, '(A200)') string
+        call check_formatter(trim(adjustl(string)), 'It is a string.', 'Value')
+        close(unit)
+
+    end subroutine test_io_disp_string
+
+end module test_io_disp
+
+program tester
+    use test_io_disp
+    call test_io_disp_complex
+    call test_io_disp_real
+    call test_io_disp_integer
+    call test_io_disp_logical
+    call test_io_disp_string
+end program tester

From fce189c9644f245b319f4c970baf1d94c05d31f9 Mon Sep 17 00:00:00 2001
From: zoziha13 <1325686572@qq.com>
Date: Mon, 12 Jul 2021 08:50:48 +0800
Subject: [PATCH 09/14] Add support for `string_type` type initially.

---
 src/stdlib_io.fypp            | 11 +++++++--
 src/stdlib_io_disp.fypp       | 25 +++++++++++++++++--
 src/tests/io/test_io_disp.f90 | 46 ++++++++++++++++++++++++-----------
 3 files changed, 64 insertions(+), 18 deletions(-)

diff --git a/src/stdlib_io.fypp b/src/stdlib_io.fypp
index a3a38bb59..f89a904f2 100644
--- a/src/stdlib_io.fypp
+++ b/src/stdlib_io.fypp
@@ -37,12 +37,19 @@ module stdlib_io
     end subroutine disp_${rank}$_${type[0]}$${kind}$
     #:endfor
     #:endfor
-    module subroutine disp_str(value, unit, header, brief)
+    module subroutine disp_character(value, unit, header, brief)
         character(len=*), intent(in), optional :: value
         integer, intent(in), optional :: unit
         character(len=*), intent(in), optional :: header
         logical, intent(in), optional :: brief
-    end subroutine disp_str
+    end subroutine disp_character
+    module subroutine disp_string_type(value, unit, header, brief)
+        use stdlib_string_type, only: string_type
+        type(string_type), intent(in) :: value
+        integer, intent(in), optional :: unit
+        character(len=*), intent(in), optional :: header
+        logical, intent(in), optional :: brief
+    end subroutine disp_string_type
   end interface disp
 
   interface loadtxt
diff --git a/src/stdlib_io_disp.fypp b/src/stdlib_io_disp.fypp
index e6ccf3871..ca90a3529 100644
--- a/src/stdlib_io_disp.fypp
+++ b/src/stdlib_io_disp.fypp
@@ -5,6 +5,7 @@ submodule (stdlib_io) stdlib_io_disp
 
     use stdlib_ascii, only: to_string
     use stdlib_strings, only: format_to_string
+    use stdlib_string_type, only: string_type, char
     use, intrinsic :: iso_fortran_env, only: output_unit
     implicit none
     character(len=*), parameter :: fmt_r = '(*(g12.4, 1x))'
@@ -33,8 +34,10 @@ contains
         if(present(header)) write(unit_, *) header
         write(unit_, *) '[vector size: '//to_string(m)//']'
         if(brief_ .and. m > 5) then
+            !! Brief Print.
             write(unit_, fmt_r) value(1:3), '...', value(m)
         else
+            !! Full Print.
             write(unit_, fmt_r) value(:)
         end if
     end procedure disp_1_${type[0]}$${kind}$
@@ -49,9 +52,11 @@ contains
         brief_ = merge(brief, .false., present(brief))
         m = size(value, 1)
         n = size(value, 2)
+
         if(present(header)) write(unit_, *) header
         write(unit_, *) '[matrix size: '//to_string(m)//'×'//to_string(n)//']'
         if(brief_ .and. (m > 5 .or. n > 5)) then
+            !! Brief Print.
             if(m > 5 .and. n > 5) then
                 do i = 1, 3
                     write(unit_, fmt_r) value(i,1:3), '...', value(i,n)
@@ -71,6 +76,7 @@ contains
                 end do
             end if
         else
+            !! Full Print.
             do i = 1, m
                 write(unit_, fmt_r) value(i,:)
             end do
@@ -95,12 +101,15 @@ contains
         unit_  = merge(unit, output_unit, present(unit))
         brief_ = merge(brief, .false., present(brief))
         m = size(value, 1)
+
         if(present(header)) write(unit_, *) header
         write(unit_, *) '[vector size: '//to_string(m)//']'
         if(brief_ .and. m > 5) then
+            !! Brief Print.
             write(unit_, fmt_c) (format_to_string(value(i), format_), i=1, 3), &
                           '...', format_to_string(value(m), format_)
         else
+            !! Full Print.
             write(unit_, fmt_c) (format_to_string(value(i), format_), i=1, m)
         end if
     end procedure disp_1_${type[0]}$${kind}$
@@ -115,9 +124,11 @@ contains
         brief_ = merge(brief, .false., present(brief))
         m = size(value, 1)
         n = size(value, 2)
+
         if(present(header)) write(unit_, *) header
         write(unit_, *) '[matrix size: '//to_string(m)//'×'//to_string(n)//']'
         if(brief_ .and. (m > 5 .or. n > 5)) then
+            !! Brief Print.
             if(m > 5 .and. n > 5) then
                 do i = 1, 3
                     write(unit_, fmt_c) (format_to_string(value(i,j), format_), j=1, 3), &
@@ -140,6 +151,7 @@ contains
                 end do
             end if
         else
+            !! Full Print.
             do i = 1, m
                 write(unit_, fmt_c) (format_to_string(value(i,j), format_), j=1, n)
             end do
@@ -147,7 +159,7 @@ contains
     end procedure disp_2_${type[0]}$${kind}$
     #:endfor
 
-    module procedure disp_str
+    module procedure disp_character
         !! Display a `character` scalar.
         character(:), allocatable :: value_
         integer :: unit_
@@ -155,6 +167,15 @@ contains
         unit_  = merge(unit, output_unit, present(unit))
         if(present(header)) write(unit_, *) header
         write(unit_, *) value_
-    end procedure disp_str
+    end procedure disp_character
+
+    module procedure disp_string_type
+        !! Display a `string_type` scalar
+        integer :: unit_
+        unit_ = merge(unit, output_unit, present(unit))
+        if(present(header)) write(unit_, *) header
+        write(unit_, *) char(value)
+            !!\TODO: Need to improve ?
+    end procedure disp_string_type
 
 end submodule stdlib_io_disp
\ No newline at end of file
diff --git a/src/tests/io/test_io_disp.f90 b/src/tests/io/test_io_disp.f90
index c65be16dd..93a79f3c4 100644
--- a/src/tests/io/test_io_disp.f90
+++ b/src/tests/io/test_io_disp.f90
@@ -6,7 +6,6 @@ module test_io_disp
     implicit none
 
     integer :: unit
-    character(*), parameter :: filenanme = "./test_io_disp.tmp"
     character(len=512) :: string
 
 contains
@@ -37,7 +36,7 @@ end subroutine check_formatter
     subroutine test_io_disp_complex
         complex :: c(6,6) = (1.0, 1.0)
         ! unit = open(filenanme, 'w+t')
-        open(newunit=unit, file=filenanme)
+        open(newunit=unit, status='scratch')
         call disp(c(1,1), header='Test_io_disp_complex_scalar (brief) : ', brief=.true.)
         call disp(c(1,1), unit=unit, header='Test_io_disp_complex_scalar (brief) : ', brief=.true.)
 
@@ -121,7 +120,7 @@ subroutine test_io_disp_real
 
         real :: r(6,6) = 1.0
         ! unit = open(filenanme, 'w+t')
-        open(newunit=unit, file=filenanme)
+        open(newunit=unit, status='scratch')
         call disp(r(1,1), header='Test_io_disp_real_scalar (brief) : ', brief=.true.)
         call disp(r(1,1), unit=unit, header='Test_io_disp_real_scalar (brief) : ', brief=.true.)
 
@@ -198,7 +197,7 @@ subroutine test_io_disp_integer
 
         integer :: i(6,6) = 1
         ! unit = open(filenanme, 'w+t')
-        open(newunit=unit, file=filenanme)
+        open(newunit=unit, status='scratch')
         call disp(i(1,1), header='Test_io_disp_integer_scalar (brief) : ', brief=.true.)
         call disp(i(1,1), unit=unit, header='Test_io_disp_integer_scalar (brief) : ', brief=.true.)
 
@@ -275,7 +274,7 @@ subroutine test_io_disp_logical
 
         logical :: l(6,6) = .true.
         ! unit = open(filenanme, 'w+t')
-        open(newunit=unit, file=filenanme)
+        open(newunit=unit, status='scratch')
         call disp(l(1,1), header='Test_io_disp_logical_scalar (brief) : ', brief=.true.)
         call disp(l(1,1), unit=unit, header='Test_io_disp_logical_scalar (brief) : ', brief=.true.)
 
@@ -348,23 +347,41 @@ subroutine test_io_disp_logical
 
     end subroutine test_io_disp_logical
 
-    subroutine test_io_disp_string
+    subroutine test_io_disp_character
 
-        character(*), parameter :: str = 'It is a string.'
+        character(*), parameter :: str = 'It is a character.'
         ! unit = open(filenanme, 'w+t')
-        open(newunit=unit, file=filenanme)
-        call disp(str, header='Test_io_disp_string_scalar (brief) : ', brief=.true.)
-        call disp(str, unit=unit, header='Test_io_disp_string_scalar (brief) : ', brief=.true.)
+        open(newunit=unit, status='scratch')
+        call disp(str, header='Test_io_disp_character_scalar (brief) : ', brief=.true.)
+        call disp(str, unit=unit, header='Test_io_disp_character_scalar (brief) : ', brief=.true.)
     
         !! Checks
         rewind(unit)
         read(unit, '(A200)') string
-        call check_formatter(trim(adjustl(string)), 'Test_io_disp_string_scalar (brief) :', 'Header')
+        call check_formatter(trim(adjustl(string)), 'Test_io_disp_character_scalar (brief) :', 'Header')
         read(unit, '(A200)') string
-        call check_formatter(trim(adjustl(string)), 'It is a string.', 'Value')
+        call check_formatter(trim(adjustl(string)), 'It is a character.', 'Value')
         close(unit)
 
-    end subroutine test_io_disp_string
+    end subroutine test_io_disp_character
+
+    subroutine test_io_disp_string_type
+
+        character(*), parameter :: str = 'It is a string_type.'
+        ! unit = open(filenanme, 'w+t')
+        open(newunit=unit, status='scratch')
+        call disp(str, header='Test_io_disp_string_type_scalar (brief) : ', brief=.true.)
+        call disp(str, unit=unit, header='Test_io_disp_string_type_scalar (brief) : ', brief=.true.)
+    
+        !! Checks
+        rewind(unit)
+        read(unit, '(A200)') string
+        call check_formatter(trim(adjustl(string)), 'Test_io_disp_string_type_scalar (brief) :', 'Header')
+        read(unit, '(A200)') string
+        call check_formatter(trim(adjustl(string)), 'It is a string_type.', 'Value')
+        close(unit)
+
+    end subroutine test_io_disp_string_type
 
 end module test_io_disp
 
@@ -374,5 +391,6 @@ program tester
     call test_io_disp_real
     call test_io_disp_integer
     call test_io_disp_logical
-    call test_io_disp_string
+    call test_io_disp_character
+    call test_io_disp_string_type
 end program tester

From c6906f0375ef88d732eb3050b44b325c87f17acd Mon Sep 17 00:00:00 2001
From: zoziha13 <1325686572@qq.com>
Date: Mon, 12 Jul 2021 08:58:28 +0800
Subject: [PATCH 10/14] Update src/Makefile.manual

---
 src/Makefile.manual | 1 +
 1 file changed, 1 insertion(+)

diff --git a/src/Makefile.manual b/src/Makefile.manual
index 52836fa7a..917d3211c 100644
--- a/src/Makefile.manual
+++ b/src/Makefile.manual
@@ -149,4 +149,5 @@ stdlib_string_format_to_string.o: stdlib_strings.o
 stdlib_linalg_outer_product.o: stdlib_linalg.o
 stdlib_io_disp.o: stdlib_error.o \
     stdlib_strings.o \
+    stdlib_string_type.o \
     stdlib_io.o

From 314f9b910d5039c946d72d3803b553b7cbcddcd9 Mon Sep 17 00:00:00 2001
From: zoziha13 <1325686572@qq.com>
Date: Mon, 12 Jul 2021 09:04:17 +0800
Subject: [PATCH 11/14] Update src/Makefile.manual

---
 src/Makefile.manual | 6 ++++--
 1 file changed, 4 insertions(+), 2 deletions(-)

diff --git a/src/Makefile.manual b/src/Makefile.manual
index 917d3211c..30e4d25d1 100644
--- a/src/Makefile.manual
+++ b/src/Makefile.manual
@@ -78,7 +78,8 @@ stdlib_io.o: \
 	stdlib_error.o \
 	stdlib_optval.o \
 	stdlib_kinds.o \
-    stdlib_ascii.o
+    stdlib_ascii.o \
+    stdlib_string_type.o
 stdlib_linalg.o: \
 	stdlib_kinds.o
 stdlib_linalg_diag.o: \
@@ -150,4 +151,5 @@ stdlib_linalg_outer_product.o: stdlib_linalg.o
 stdlib_io_disp.o: stdlib_error.o \
     stdlib_strings.o \
     stdlib_string_type.o \
-    stdlib_io.o
+    stdlib_io.o \
+    stdlib_ascii.o

From dfc20062a9bfaf3abc10b118c351272d1341510d Mon Sep 17 00:00:00 2001
From: zoziha13 <1325686572@qq.com>
Date: Mon, 12 Jul 2021 09:15:52 +0800
Subject: [PATCH 12/14] Fix a bug in test_io_disp.f90 for `string_type` test.

---
 src/tests/io/test_io_disp.f90 | 4 +++-
 1 file changed, 3 insertions(+), 1 deletion(-)

diff --git a/src/tests/io/test_io_disp.f90 b/src/tests/io/test_io_disp.f90
index 93a79f3c4..b9f077c39 100644
--- a/src/tests/io/test_io_disp.f90
+++ b/src/tests/io/test_io_disp.f90
@@ -1,6 +1,7 @@
 module test_io_disp
 
     use stdlib_strings, only: starts_with
+    use stdlib_string_type, only: string_type, assignment(=)
     use stdlib_error, only: check
     use stdlib_io, only: disp, open
     implicit none
@@ -367,8 +368,9 @@ end subroutine test_io_disp_character
 
     subroutine test_io_disp_string_type
 
-        character(*), parameter :: str = 'It is a string_type.'
+        type(string_type) :: str
         ! unit = open(filenanme, 'w+t')
+        str = 'It is a string_type.'
         open(newunit=unit, status='scratch')
         call disp(str, header='Test_io_disp_string_type_scalar (brief) : ', brief=.true.)
         call disp(str, unit=unit, header='Test_io_disp_string_type_scalar (brief) : ', brief=.true.)

From 3c24a750016b333e46606e0622d753254ecc43d9 Mon Sep 17 00:00:00 2001
From: zoziha13 <1325686572@qq.com>
Date: Wed, 14 Jul 2021 09:03:21 +0800
Subject: [PATCH 13/14] Update stdlib_io%disp.md

---
 doc/specs/stdlib_io.md | 5 +++--
 1 file changed, 3 insertions(+), 2 deletions(-)

diff --git a/doc/specs/stdlib_io.md b/doc/specs/stdlib_io.md
index 8ecf49c3e..3297f4be2 100644
--- a/doc/specs/stdlib_io.md
+++ b/doc/specs/stdlib_io.md
@@ -139,7 +139,8 @@ end program demo_savetxt
 Experimental
 
 ### Description
-Display any type of scalar, vector or matrix.
+Display any type (`logical, integer, real, complex, character, string_type`) of scalar,   
+and display some data type (`logical, integer, real, complex`) of vector or matrix.
 
 Make good use of similar to the following usage, can help you understand the data information in the `array`.
 ```fortran
@@ -159,7 +160,7 @@ For null:
 
 ### Arguments
 
-`value`: Shall be any type of scalar, vector or matrix.
+`value`: Shall be any type of scalar, and some data type (`logical, integer, real, complex`) of vector or matrix.
     This is an `intent(in)` argument.
 
 `unit`: Shall be an `integer` scalar link to an IO stream.

From 92fe853c9624d0bf0006aa0a0ffb0c2950adf9b6 Mon Sep 17 00:00:00 2001
From: zoziha13 <1325686572@qq.com>
Date: Mon, 23 Aug 2021 09:46:34 +0800
Subject: [PATCH 14/14] Meger `to_string` to `disp`, update `disp` routines.

---
 doc/specs/stdlib_io.md        |  56 +++++----
 src/Makefile.manual           |   9 +-
 src/stdlib_io.fypp            |  28 ++---
 src/stdlib_io_disp.fypp       | 220 ++++++++++++++++++----------------
 src/tests/io/test_io_disp.f90 |  30 +++--
 5 files changed, 186 insertions(+), 157 deletions(-)

diff --git a/doc/specs/stdlib_io.md b/doc/specs/stdlib_io.md
index b5dc4e356..89fd32e12 100644
--- a/doc/specs/stdlib_io.md
+++ b/doc/specs/stdlib_io.md
@@ -138,56 +138,65 @@ end program demo_savetxt
 
 Experimental
 
+### Class
+
+Impure subroutine.
+
 ### Description
-Display any type (`logical, integer, real, complex, character, string_type`) of scalar,   
-and display some data type (`logical, integer, real, complex`) of vector or matrix.
+
+Display a `logical/integer/real/complex/character/string_type` scalar or `logical/integer/real/complex` and rank-1/rank-2 array to the screen or another output `unit`.
+
+#### More details
 
 Make good use of similar to the following usage, can help you understand the data information in the `array`.
 ```fortran
-call disp( A(i, j, 2, :, 1:10) [, unit, header, brief] )    !! `i, j, ...` can be determined by `do` loop.
+call disp( A(i, j, 2, :, 1:10) [, header, unit, brief] )    !! `i, j, ...` can be determined by `do` loop.
 ```
 
 Generally, except for `complex` type, any other type of scalar or single element of the `array` will be printed out with a width of 12 characters and a space separator.  
 For `complex` type, scalar or single element of the `array` will be printed out with a width of 25 characters and a space separator.
 
 In order to prevent users from accidentally passing large-length arrays to `disp`, causing unnecessary io blockage:
-1. If the `brief` argument is not specified, `disp` will print **the brief array content with a length of 10*50 by default**.
-2. Specify `brief=.true.`, `disp` will print **the brief array content with a length of 5*5**;
-3. Specify `brief=.false.`, `disp` will print **all the contents of the array** (please print all the contents of the array as appropriate according to the actual situation to avoid unnecessary IO blockage and affect the reading experience)
+1. If the `brief` argument is not specified, `disp` will print **the brief array content with a length of `10*50` by default**.
+2. Specify `brief=.true.`, `disp` will print **the brief array content with a length of `5*5`**;
+3. Specify `brief=.false.`, `disp` will print **`all` the contents of the array** (please print all the contents of the array as appropriate according to the actual situation to avoid unnecessary IO blockage and affect the reading experience)
 
 ### Syntax
 
-General API:
-`call [[stdlib_io(module):disp(interface)]](value [, unit, header, brief])`
-
-For null:
-`call [[stdlib_io(module):disp(interface)]]()`  
+`call [[stdlib_io(module):disp(interface)]]([value, header, unit, brief])`  
 
 ### Arguments
 
-`value`: Shall be any type of scalar, and some data type (`logical, integer, real, complex`) of vector or matrix.
-    This is an `intent(in)` argument.
+`value`: Shall be a `logical/integer/real/complex/string_type` scalar or `logical/integer/real/complex` and rank-1/rank-2 array.
+This argument is `intent(in)` and `optional`.
 
-`unit`: Shall be an `integer` scalar link to an IO stream.
-    This is an `intent(in)` and `optional` argument.
+`header`: Shall be a `character(len=*)` scalar. 
+This argument is `intent(in)` and `optional`.  
+Usually used to comment data information.
 
-`header`: Shall be a scalar of type `character` with any length (usually used to comment data information).
-    This is an `intent(in)` and `optional` argument.
+`unit`: Shall be an `integer` scalar linked to an IO stream.
+This argument is `intent(in)` and `optional`.
+Indicates the output `unit`.
 
-`brief`: Shall be an `logical` scalar, controlling an abridged version of the `value` object is printed.
-    This is an `intent(in)` and `optional` argument.
+`brief`: Shall be a `logical` scalar.
+This argument is `intent(in)` and `optional`.  
+Controls an abridged version of the `value` object is printed.
 
 ### Output
 
-The result is to print `header` and `value` on the screen (or another output unit) in this order.  
-If `value` is a `array` type, the dimension length information of the `array` will also be outputted.
+The result is to print `header` and `value` on the screen (or another output `unit`) in this order.  
+If `value` is a rank-1/rank-2 `array` type, the dimension length information of the `array` will also be outputted.
+
+If `disp` is not passed any arguments, a blank line is printed.
+
+If the `value` is present and of `real/complex` type, the data will retain four significant decimal places, like `(g0.4)`.
 
 ### Example
 
 ```fortran
 program test_io_disp
     
-    use :: stdlib_io, only: disp
+    use stdlib_io, only: disp
     implicit none
     real(8) :: r(2, 3)
     complex :: c(2, 3), c_3d(2, 100, 20)
@@ -200,6 +209,7 @@ program test_io_disp
     c(2, 2) = (-1.e10,-1.e10)
     c_3d(1,3,1) = (1000, 0.001)
     c_3d(1,3,2) = (1.e4, 100.)
+
     call disp('string', header='disp(string):')
     call disp('It is a note.')
     call disp()
@@ -215,7 +225,7 @@ program test_io_disp
 
 end program test_io_disp
 ```
-**Result:**
+**Results:**
 ```fortran
  disp(string):
  string
diff --git a/src/Makefile.manual b/src/Makefile.manual
index 3a3302c0d..3b55cc06f 100644
--- a/src/Makefile.manual
+++ b/src/Makefile.manual
@@ -79,13 +79,11 @@ stdlib_bitsets_large.o: stdlib_bitsets.o
 stdlib_error.o: stdlib_optval.o
 stdlib_specialfunctions.o: stdlib_kinds.o
 stdlib_specialfunctions_legendre.o: stdlib_kinds.o stdlib_specialfunctions.o
-stdlib_io.o: 
-    stdlib_ascii.o \
+stdlib_io.o: \
     stdlib_error.o \
     stdlib_optval.o \
     stdlib_kinds.o \
     stdlib_ascii.o \
-    stdlib_error.o \
     stdlib_string_type.o
 stdlib_linalg.o: \
     stdlib_kinds.o
@@ -168,8 +166,7 @@ stdlib_math_logspace.o: \
 stdlib_math_arange.o: \
     stdlib_math.o
 stdlib_linalg_outer_product.o: stdlib_linalg.o
-stdlib_io_disp.o: stdlib_error.o \
+stdlib_io_disp.o: \
     stdlib_strings.o \
     stdlib_string_type.o \
-    stdlib_io.o \
-    stdlib_ascii.o
+    stdlib_io.o
diff --git a/src/stdlib_io.fypp b/src/stdlib_io.fypp
index f89a904f2..efc675f0a 100644
--- a/src/stdlib_io.fypp
+++ b/src/stdlib_io.fypp
@@ -11,6 +11,7 @@ module stdlib_io
   use stdlib_error, only: error_stop
   use stdlib_optval, only: optval
   use stdlib_ascii, only: is_blank
+  use stdlib_string_type, only: string_type
   implicit none
   private
   ! Public API
@@ -19,35 +20,34 @@ module stdlib_io
   ! Private API that is exposed so that we can test it in tests
   public :: parse_mode
 
+  !> version: experimental
+  !>
+  !> Display a scalar, vector or matrix.
+  !> ([Specification](../page/specs/stdlib_io.html#disp-display-your-data-to-the-screen-or-another-output-unit))
   interface disp
-    !! version: experimental
-    !!
-    !! Display any type of scalar, vector and matrix.
-    !! ([Specification](../page/specs/stdlib_io.html#disp-display-your-data-to-the-screen-or-another-output-unit))
     #:set DISP_KINDS_TYPES = REAL_KINDS_TYPES + INT_KINDS_TYPES &
         & + CMPLX_KINDS_TYPES + LOG_KINDS_TYPES
     #:set DISP_RANKS = range(0, 3)
-    #:for kind, type in DISP_KINDS_TYPES
+    #:for k1, t1 in DISP_KINDS_TYPES
     #:for rank in DISP_RANKS
-    module subroutine disp_${rank}$_${type[0]}$${kind}$(value, unit, header, brief)
-        ${type}$, intent(in) :: value${ranksuffix(rank)}$
-        integer, intent(in), optional :: unit
+    module subroutine disp_${rank}$_${t1[0]}$${k1}$(value, header, unit, brief)
+        ${t1}$, intent(in) :: value${ranksuffix(rank)}$
         character(len=*), intent(in), optional :: header
+        integer, intent(in), optional :: unit
         logical, intent(in), optional :: brief
-    end subroutine disp_${rank}$_${type[0]}$${kind}$
+    end subroutine disp_${rank}$_${t1[0]}$${k1}$
     #:endfor
     #:endfor
-    module subroutine disp_character(value, unit, header, brief)
+    module subroutine disp_character(value, header, unit, brief)
         character(len=*), intent(in), optional :: value
-        integer, intent(in), optional :: unit
         character(len=*), intent(in), optional :: header
+        integer, intent(in), optional :: unit
         logical, intent(in), optional :: brief
     end subroutine disp_character
-    module subroutine disp_string_type(value, unit, header, brief)
-        use stdlib_string_type, only: string_type
+    module subroutine disp_string_type(value, header, unit, brief)
         type(string_type), intent(in) :: value
-        integer, intent(in), optional :: unit
         character(len=*), intent(in), optional :: header
+        integer, intent(in), optional :: unit
         logical, intent(in), optional :: brief
     end subroutine disp_string_type
   end interface disp
diff --git a/src/stdlib_io_disp.fypp b/src/stdlib_io_disp.fypp
index 6ca02f4e8..623d42808 100644
--- a/src/stdlib_io_disp.fypp
+++ b/src/stdlib_io_disp.fypp
@@ -3,15 +3,14 @@
 
 submodule (stdlib_io) stdlib_io_disp
 
-    use stdlib_ascii, only: to_string
-    use stdlib_strings, only: format_to_string
-    use stdlib_string_type, only: string_type, char
+    use stdlib_strings, only: to_string
+    use stdlib_string_type, only: char
     use, intrinsic :: iso_fortran_env, only: output_unit
     implicit none
     
     character(len=*), parameter :: fmt_r = '(*(g12.4, 1x))'
     character(len=*), parameter :: fmt_c = '(*(g25.0, 1x))'
-    character(len=*), parameter :: format_ = '(g0.4)'
+    character(len=*), parameter :: format_ = 'g0.4'
     integer, parameter :: brief_col = 5
     integer, parameter :: brief_row = 5
     integer, parameter :: default_col = 10
@@ -19,178 +18,197 @@ submodule (stdlib_io) stdlib_io_disp
     
 contains
     
-    #:for kind, type in RIL_KINDS_TYPES
-    module procedure disp_0_${type[0]}$${kind}$
-        !! Display a/an ${type}$ scalar.
+    #:for k1, t1 in RIL_KINDS_TYPES
+    !> Display a/an ${t1}$ scalar.
+    module procedure disp_0_${t1[0]}$${k1}$
         integer :: unit_
-        unit_  = merge(unit, output_unit, present(unit))
-        if(present(header)) write(unit_, *) header
+
+        unit_ = optval(unit, output_unit)
+
+        if (present(header)) write(unit_, *) header
         write(unit_, fmt_r) value
-    end procedure disp_0_${type[0]}$${kind}$
 
-    module procedure disp_1_${type[0]}$${kind}$
-        !! Display a/an ${type}$ vector.
+    end procedure disp_0_${t1[0]}$${k1}$
+
+    !> Display a/an ${t1}$ vector.
+    module procedure disp_1_${t1[0]}$${k1}$
         integer :: unit_
         logical :: brief_
         integer :: m, col
-        unit_  = merge(unit, output_unit, present(unit))
-        brief_ = merge(brief, .true., present(brief))
-        col = merge(brief_col, default_col, present(brief) .and. brief_)
-        m = size(value, 1)
-
-        if(present(header)) write(unit_, *) header
-        write(unit_, *) '[vector size: '//to_string(m)//']'
-        if(brief_ .and. m > col) then
-            !! Brief Print.
+        
+        unit_  = optval(unit, output_unit)
+        brief_ = optval(brief, .true.)
+        col    = merge(brief_col, default_col, present(brief) .and. brief_)
+        m      = size(value, 1)
+
+        if (present(header)) write(unit_, *) header
+        write(unit_, *) '[vector size: ' // to_string(m) // ']'
+        if (brief_ .and. m > col) then
+            !> Brief Print.
             write(unit_, fmt_r) value(1:col-2), '...', value(m)
         else
-            !! Full Print.
+            !> Full Print.
             write(unit_, fmt_r) value(:)
         end if
-    end procedure disp_1_${type[0]}$${kind}$
 
-    module procedure disp_2_${type[0]}$${kind}$
-        !! Display a/an ${type}$ matrix.
+    end procedure disp_1_${t1[0]}$${k1}$
+
+    !> Display a/an ${t1}$ matrix.
+    module procedure disp_2_${t1[0]}$${k1}$
         integer :: unit_
         logical :: brief_
         integer :: i, m, n
         integer :: col, row
-        character(1) :: colon(default_col)
-
-        unit_  = merge(unit, output_unit, present(unit))
-        brief_ = merge(brief, .true., present(brief))
-        col = merge(brief_col, default_col, present(brief) .and. brief_)
-        row = merge(brief_row, default_row, present(brief) .and. brief_)
-        m = size(value, 1)
-        n = size(value, 2)
-
-        if(present(header)) write(unit_, *) header
-        write(unit_, *) '[matrix size: '//to_string(m)//'×'//to_string(n)//']'
-        if(brief_ .and. (m > col .or. n > row)) then
-            !! Brief Print.
+        character(len=1) :: colon(default_col)
+
+        unit_  = optval(unit, output_unit)
+        brief_ = optval(brief, .true.)
+        col    = merge(brief_col, default_col, present(brief) .and. brief_)
+        row    = merge(brief_row, default_row, present(brief) .and. brief_)
+        m      = size(value, 1)
+        n      = size(value, 2)
+
+        if (present(header)) write(unit_, *) header
+        write(unit_, *) '[matrix size: ' // to_string(m) // '×' // to_string(n) // ']'
+        if (brief_ .and. (m > col .or. n > row)) then
+            !> Brief Print.
             colon = ':'
-            if(m > col .and. n > row) then
+            if (m > col .and. n > row) then
                 do i = 1, row-2
                     write(unit_, fmt_r) value(i,1:col-2), '...', value(i,n)
                 end do
                 write(unit_, fmt_r) colon(1:col)
                 write(unit_, fmt_r) value(m,1:col-2), '...', value(m,n)
-            elseif(m > col .and. n <= row) then
+            elseif (m > col .and. n <= row) then
                 do i = 1, 3
                     write(unit_, fmt_r) value(i,:)
                 end do
                 write(unit_, fmt_r) colon(1:n)
                 write(unit_, fmt_r) value(m,:)
-            elseif(m <= col .and. n > row) then
+            elseif (m <= col .and. n > row) then
                 do i = 1, m
                     write(unit_, fmt_r) value(i,1:col-2), '...', value(i,n)
                 end do
             end if
         else
-            !! Full Print.
+            !> Full Print.
             do i = 1, m
                 write(unit_, fmt_r) value(i,:)
             end do
         end if
-    end procedure disp_2_${type[0]}$${kind}$
+
+    end procedure disp_2_${t1[0]}$${k1}$
     #:endfor
 
-    #:for kind, type in CMPLX_KINDS_TYPES
-    module procedure disp_0_${type[0]}$${kind}$
-        !! Display a ${type}$ scalar.
+    #:for k1, t1 in CMPLX_KINDS_TYPES
+    !> Display a ${t1}$ scalar.
+    module procedure disp_0_${t1[0]}$${k1}$
         integer :: unit_
-        unit_  = merge(unit, output_unit, present(unit))
-        if(present(header)) write(unit_, *) header
-        write(unit_, fmt_c) format_to_string(value, format_)
-    end procedure disp_0_${type[0]}$${kind}$
 
-    module procedure disp_1_${type[0]}$${kind}$
-        !! Display a ${type}$ vector.
+        unit_  = optval(unit, output_unit)
+
+        if (present(header)) write(unit_, *) header
+        write(unit_, fmt_c) to_string(value, format_)
+
+    end procedure disp_0_${t1[0]}$${k1}$
+
+    !> Display a ${t1}$ vector.
+    module procedure disp_1_${t1[0]}$${k1}$
         integer :: unit_
         logical :: brief_
         integer :: i, m, col
-        unit_  = merge(unit, output_unit, present(unit))
-        brief_ = merge(brief, .true., present(brief))
-        col = merge(brief_col, default_col, present(brief) .and. brief_)
-        m = size(value, 1)
-
-        if(present(header)) write(unit_, *) header
-        write(unit_, *) '[vector size: '//to_string(m)//']'
-        if(brief_ .and. m > col) then
-            !! Brief Print.
-            write(unit_, fmt_c) (format_to_string(value(i), format_), i=1, col-2), &
-                          '...', format_to_string(value(m), format_)
+
+        unit_  = optval(unit, output_unit)
+        brief_ = optval(brief, .true.)
+        col    = merge(brief_col, default_col, present(brief) .and. brief_)
+        m      = size(value, 1)
+
+        if (present(header)) write(unit_, *) header
+        write(unit_, *) '[vector size: ' // to_string(m) // ']'
+        if (brief_ .and. m > col) then
+            !> Brief Print.
+            write(unit_, fmt_c) (to_string(value(i), format_), i=1, col-2), &
+                          '...', to_string(value(m), format_)
         else
-            !! Full Print.
-            write(unit_, fmt_c) (format_to_string(value(i), format_), i=1, m)
+            !> Full Print.
+            write(unit_, fmt_c) (to_string(value(i), format_), i=1, m)
         end if
-    end procedure disp_1_${type[0]}$${kind}$
 
-    module procedure disp_2_${type[0]}$${kind}$
-        !! Display a ${type}$ matrix.
+    end procedure disp_1_${t1[0]}$${k1}$
+
+    !> Display a ${t1}$ matrix.
+    module procedure disp_2_${t1[0]}$${k1}$
         integer :: unit_
         logical :: brief_
         integer :: i, j, m, n
         integer :: col, row
-        character(1) :: colon(default_col)
-        unit_  = merge(unit, output_unit, present(unit))
-        brief_ = merge(brief, .true., present(brief))
-        col = merge(brief_col, default_col, present(brief) .and. brief_)
-        row = merge(brief_row, default_row, present(brief) .and. brief_)
-        m = size(value, 1)
-        n = size(value, 2)
-
-        if(present(header)) write(unit_, *) header
-        write(unit_, *) '[matrix size: '//to_string(m)//'×'//to_string(n)//']'
-        if(brief_ .and. (m > col .or. n > row)) then
-            !! Brief Print.
+        character(len=1) :: colon(default_col)
+
+        unit_  = optval(unit, output_unit)
+        brief_ = optval(brief, .true.)
+        col    = merge(brief_col, default_col, present(brief) .and. brief_)
+        row    = merge(brief_row, default_row, present(brief) .and. brief_)
+        m      = size(value, 1)
+        n      = size(value, 2)
+
+        if (present(header)) write(unit_, *) header
+        write(unit_, *) '[matrix size: ' // to_string(m) // '×' // to_string(n) // ']'
+        if (brief_ .and. (m > col .or. n > row)) then
+            !> Brief Print.
             colon = ':'
-            if(m > col .and. n > row) then
+            if (m > col .and. n > row) then
                 do i = 1, col-2
-                    write(unit_, fmt_c) (format_to_string(value(i,j), format_), j=1, col-2), &
-                                  '...', format_to_string(value(i,n), format_)
+                    write(unit_, fmt_c) (to_string(value(i,j), format_), j=1, col-2), &
+                                  '...', to_string(value(i,n), format_)
                 end do
                 write(unit_, fmt_c) colon(1:col)
-                write(unit_, fmt_c) (format_to_string(value(m,j), format_), j=1, col-2), &
-                              '...', format_to_string(value(m,n), format_)
-            elseif(m > col .and. n <= row) then
+                write(unit_, fmt_c) (to_string(value(m,j), format_), j=1, col-2), &
+                              '...', to_string(value(m,n), format_)
+            elseif (m > col .and. n <= row) then
                 do i = 1, col-2
-                    write(unit_, fmt_c) (format_to_string(value(i,j), format_), j=1, n)
+                    write(unit_, fmt_c) (to_string(value(i,j), format_), j=1, n)
                 end do
                 write(unit_, fmt_c) colon(1:n)
-                write(unit_, fmt_c) (format_to_string(value(m,j), format_), j=1, n)
-            elseif(m <= col .and. n > row) then
+                write(unit_, fmt_c) (to_string(value(m,j), format_), j=1, n)
+            elseif (m <= col .and. n > row) then
                 do i = 1, m
-                    write(unit_, fmt_c) (format_to_string(value(m,j), format_), j=1, col-2), &
-                                  '...', format_to_string(value(m,n), format_)
+                    write(unit_, fmt_c) (to_string(value(m,j), format_), j=1, col-2), &
+                                  '...', to_string(value(m,n), format_)
                 end do
             end if
         else
-            !! Full Print.
+            !> Full Print.
             do i = 1, m
-                write(unit_, fmt_c) (format_to_string(value(i,j), format_), j=1, n)
+                write(unit_, fmt_c) (to_string(value(i,j), format_), j=1, n)
             end do
         end if
-    end procedure disp_2_${type[0]}$${kind}$
+
+    end procedure disp_2_${t1[0]}$${k1}$
     #:endfor
 
+    !> Display a `character` scalar.
     module procedure disp_character
-        !! Display a `character` scalar.
-        character(:), allocatable :: value_
+        character(len=:), allocatable :: value_
         integer :: unit_
+
         value_ = optval(value, '')
-        unit_  = merge(unit, output_unit, present(unit))
-        if(present(header)) write(unit_, *) header
+        unit_  = optval(unit, output_unit)
+
+        if (present(header)) write(unit_, *) header
         write(unit_, *) value_
+
     end procedure disp_character
 
+    !> Display a `string_type` scalar
     module procedure disp_string_type
-        !! Display a `string_type` scalar
         integer :: unit_
-        unit_ = merge(unit, output_unit, present(unit))
-        if(present(header)) write(unit_, *) header
+
+        unit_ = optval(unit, output_unit)
+
+        if (present(header)) write(unit_, *) header
         write(unit_, *) char(value)
             !!\TODO: Need to improve ?
+
     end procedure disp_string_type
 
 end submodule stdlib_io_disp
\ No newline at end of file
diff --git a/src/tests/io/test_io_disp.f90 b/src/tests/io/test_io_disp.f90
index a61e0fba9..ed4781ab5 100644
--- a/src/tests/io/test_io_disp.f90
+++ b/src/tests/io/test_io_disp.f90
@@ -4,10 +4,11 @@ module test_io_disp
     use stdlib_string_type, only: string_type, assignment(=)
     use stdlib_error, only: check
     use stdlib_io, only: disp
+    use stdlib_optval, only: optval
     implicit none
 
     integer :: unit
-    character(len=512) :: string
+    character(len=200) :: string
 
 contains
 
@@ -17,7 +18,7 @@ subroutine check_formatter(actual, expected, description, partial)
         logical :: stat
         character(len=:), allocatable :: msg
 
-        if (merge(partial, .false., present(partial))) then
+        if (optval(partial, .false.)) then
             stat = starts_with(actual, expected)
         else
             stat = actual == expected
@@ -36,7 +37,7 @@ end subroutine check_formatter
 
     subroutine test_io_disp_complex
         complex :: c(6,6) = (1.0, 1.0)
-        ! unit = open(filenanme, 'w+t')
+
         open(newunit=unit, status='scratch')
         call disp(c(1,1), header='Test_io_disp_complex_scalar (brief) : ', brief=.true.)
         call disp(c(1,1), unit=unit, header='Test_io_disp_complex_scalar (brief) : ', brief=.true.)
@@ -120,7 +121,7 @@ end subroutine test_io_disp_complex
     subroutine test_io_disp_real
 
         real :: r(6,6) = 1.0
-        ! unit = open(filenanme, 'w+t')
+        
         open(newunit=unit, status='scratch')
         call disp(r(1,1), header='Test_io_disp_real_scalar (brief) : ', brief=.true.)
         call disp(r(1,1), unit=unit, header='Test_io_disp_real_scalar (brief) : ', brief=.true.)
@@ -197,7 +198,7 @@ end subroutine test_io_disp_real
     subroutine test_io_disp_integer
 
         integer :: i(6,6) = 1
-        ! unit = open(filenanme, 'w+t')
+        
         open(newunit=unit, status='scratch')
         call disp(i(1,1), header='Test_io_disp_integer_scalar (brief) : ', brief=.true.)
         call disp(i(1,1), unit=unit, header='Test_io_disp_integer_scalar (brief) : ', brief=.true.)
@@ -369,7 +370,7 @@ end subroutine test_io_disp_character
     subroutine test_io_disp_string_type
 
         type(string_type) :: str
-        ! unit = open(filenanme, 'w+t')
+        
         str = 'It is a string_type.'
         open(newunit=unit, status='scratch')
         call disp(str, header='Test_io_disp_string_type_scalar (brief) : ', brief=.true.)
@@ -388,8 +389,10 @@ end subroutine test_io_disp_string_type
 end module test_io_disp
 
 program tester
+
     use test_io_disp
-    real(4) :: x(51,51)
+    ! real(4) :: x(51,51)
+
     call test_io_disp_complex
     call test_io_disp_real
     call test_io_disp_integer
@@ -397,10 +400,11 @@ program tester
     call test_io_disp_character
     call test_io_disp_string_type
 
-    !! Content that is difficult to test: The length of the dimension is too large
-    !!  to print and check by a test program.
-    x = 0.0
-    call disp(x, header="Test_io_disp_real_matrix (51×51)(default) : [10×50]")
-    call disp(x, header="Test_io_disp_real_matrix (51×51)(brief=.true.) : [5×5]", brief=.true.)
-    call disp(x, header="Test_io_disp_real_matrix (51×51)(brief=.false.) : [all]", brief=.false.)
+    !> Content that is difficult to test: The length of the dimension is too large
+    !>  to print and check by a test program.
+    ! x = 0.0
+    ! call disp(x, header="Test_io_disp_real_matrix (51×51)(default) : [10×50]")
+    ! call disp(x, header="Test_io_disp_real_matrix (51×51)(brief=.true.) : [5×5]", brief=.true.)
+    ! call disp(x, header="Test_io_disp_real_matrix (51×51)(brief=.false.) : [all]", brief=.false.)
+
 end program tester