Potential chapter 2 compile errors FIXES

[F-Kearney]

Just a few things that tripped me up while following along:

The functions ht_new and ht_del_hash_table are used in main.c but aren’t declared in hash_table.h. This causes an “implicit declaration” compiler error. Adding the declarations to the header file fixes it:

ht_hash_table* ht_new(void);
void ht_del_hash_table(ht_hash_table* ht);

The code uses strdup, which isn’t part of the C standard library by default — it’s POSIX. On some systems (like when compiling with gcc -Wall -Wextra -std=c99), you’ll get an “incompatible integer to pointer conversion” error unless you define the right macro. Adding this flag fixes it:

-D_POSIX_C_SOURCE=200809L

Might be worth adding a note that you need to compile both main.c and hash_table.c, like:

gcc -g -Wall -Wextra -D_POSIX_C_SOURCE=200809L main.c hash_table.c -o program

Hope this helps others avoid the same confusion. Cheers!