diff --git a/README.md b/README.md
index 5f1a4f2..ee2b1b4 100644
--- a/README.md
+++ b/README.md
@@ -28,7 +28,7 @@ void loop()
 ```ino
 #include <HCSR04.h>
 
-HCSR04 hc(2,new int[6]{5,6,7,8,9,10});//initialisation class HCSR04 (trig pin , echo pin)
+HCSR04 hc(2,new int[6]{5,6,7,8,9,10},6);//initialisation class HCSR04 (trig pin , echo pins, number of sensors)
 
 void setup()
 { Serial.begin(9600); }
diff --git a/examples/HCSR04_multi/HCSR04_multi.ino b/examples/HCSR04_multi/HCSR04_multi.ino
index 52903a6..1cb3716 100644
--- a/examples/HCSR04_multi/HCSR04_multi.ino
+++ b/examples/HCSR04_multi/HCSR04_multi.ino
@@ -1,6 +1,6 @@
 #include <HCSR04.h>
 
-HCSR04 hc(2,new int[6]{5,6,7,8,9,10});//initialisation class HCSR04 (trig pin , echo pin)
+HCSR04 hc(2,new int[6]{5,6,7,8,9,10},6);//initialisation class HCSR04 (trig pin , echo pin, number of sensor)
 
 void setup()
 { Serial.begin(9600); }
diff --git a/library.properties b/library.properties
index d9e7c58..3c1ad13 100644
--- a/library.properties
+++ b/library.properties
@@ -1,5 +1,5 @@
 name=HCSR04 ultrasonic sensor
-version=2.0.0
+version=2.0.1
 author=gamegine
 maintainer=gamegine
 sentence=Allows an Arduino board to use HCSR04 module.
diff --git a/src/HCSR04.cpp b/src/HCSR04.cpp
index 0339e96..905bb2d 100644
--- a/src/HCSR04.cpp
+++ b/src/HCSR04.cpp
@@ -1,19 +1,20 @@
 #include "HCSR04.h"
 ////////////////////////////////////consttruct/destruct
-void HCSR04::init(int out,int echo[])
+void HCSR04::init(int out,int echo[],int n)
 {
 	this->out = out;
 	this->echo = echo;
+	this->n = n;
 	pinMode(this->out, OUTPUT);
-	for(int i=0;i<sizeof(echo);i++)
-	{ pinMode(this->echo[i], INPUT); }
+	for(int i=0;i<n;i++){ pinMode(this->echo[i], INPUT); }
 }
-HCSR04::HCSR04(int out,int echo){this->init(out,new int[1]{echo});}
-HCSR04::HCSR04(int out,int echo[]){this->init(out,echo);}
+HCSR04::HCSR04(int out,int echo){this->init(out,new int[1]{echo},1);}
+HCSR04::HCSR04(int out,int echo[],int n){this->init(out,echo,n);}
 HCSR04::~HCSR04()
 {
 	~this->out;
 	delete[] this->echo;
+	~this->n;
 }
 ///////////////////////////////////////////////////dist
 float HCSR04::dist(int n) const
diff --git a/src/HCSR04.h b/src/HCSR04.h
index fa6f4ac..cbc03e5 100644
--- a/src/HCSR04.h
+++ b/src/HCSR04.h
@@ -3,13 +3,14 @@ class HCSR04
 {
 	public:
 	HCSR04(int out,int echo);				//initialisation class HCSR04 (trig pin , echo pin)
-	HCSR04(int out,int echo[]);				//initialisation class HCSR04 (trig pin , echo pin)
+	HCSR04(int out,int echo[],int n);		//initialisation class HCSR04 (trig pin , echo pin)
 	~HCSR04();								//destructor
 	float dist()      const;				//return curent distance of element 0
 	float dist(int n)      const;				//return curent distance of element 0
 
 	private:
-	void init(int out,int echo[]); 			//for constructor
+	void init(int out,int echo[],int n); 			//for constructor
 	int out;								//out pin
 	int *echo;								//echo pin list
+	int n;									//number of el
 };