Warning: implicit declaration of the 'kill' function

Question

I do these inclusions:

#include <signal.h> #include <unistd.h> #include <sys/types.h> #include <sys/wait.h> 

But still getting this warning.

Answer 1

You are probably passing the "-ansi -Wall" switches to the gcc compiler. You can remove "-ansi" if you do not need it, otherwise try setting the appropriate function definition macro.

Sort of:

 #define _POSIX_SOURCE #include <sys/types.h> #include <signal.h> #include <unistd.h> #include <sys/wait.h> 

Answer 2

You can also define it at compile time by adding this flag with gcc.

 -D_POSIX_C_SOURCE 

Example:

 -g -D_POSIX_C_SOURCE -Wall -std=c99