How do you call a C program from within another C program

Question

I have two C programs, Project1A.c and Project1B.c. I'm trying to use execl() to execute Project1A from inside Project1B but so far it's not working.

Project1B.c

#include <stdio.h>
#include <stdlib.h>
#include <sys/types.h>
#include <unistd.h>

int main ()
{
  pid_t pid;

  switch((pid = fork()))
  {
    case -1:
      printf("I'm sorry, fork failed\n");
      break;
    case 0:
      execl("Project1A.c", "./prog", NULL);
      printf("EXECL Unsucessfull");
      break;
    default:
      printf("This is some parent code\n");
      break;
  }
  printf("End of Program\n");

  return 0;
}

Answer 1

execl executes a binary file, meaning you cannot pass it Project1A.c and expect it to work. You need to compile it and execute the compile program.

Subsequent arguments to the function are command-line arguments, terminated by NULL. This means that your execl call corresponds to ./Project1A.c ./prog on a shell, which obviously doesn't work.

Instead, your execl call should be: execl("prog1A", NULL);.

On a side not, you could maybe run C code by running the compile command first using the system function and then running the compiled program with execl if the compilation was successful.