Use of exit() function

Try man exit.

---

Oh, and:

#include <stdlib.h>

int main(void) {
  /*  ...  */
  if (error_occured) {
    return (EXIT_FAILURE);
  }
  /*  ...  */
  return (EXIT_SUCCESS);
}

Try using exit(0); instead. The exit function expects an integer parameter. And don't forget to #include <stdlib.h>.

The exit function is declared in the stdlib header, so you need to have

#include <stdlib.h>

at the top of your program to be able to use exit.

Note also that exit takes an integer argument, so you can't call it like exit(), you have to call as exit(0) or exit(42). 0 usually means your program completed successfully, and nonzero values are used as error codes.

There are also predefined macros EXIT_SUCCESS and EXIT_FAILURE, e.g. exit(EXIT_SUCCESS);