Killing a process with C program - c

Question

I'm writing a program that open a .txt file by vim and whenever i press CTRL+C the process will be killed. But the thing is i can't find the process's pid that i've just created and kill it. Can anybody help me?
#include <stdio.h>
#include <signal.h>
#include <stdlib.h>
#include <unistd.h>
#include <sys/types.h>
void ctrl_C(int sig){
system("kill -9 $(pidof id)");
printf("\n You pressed Ctrl + C,Good Bye \n");
exit(0);
}
int main(){
printf("I am Programmer \n");
pid_t id = system("gnome-terminal -- vi abcd.txt");
signal(SIGINT,ctrl_C);
while(1){}
}

Answer 1

There are multiple issues with your code:
system(3) does NOT return PID of child process, but instead waits for it to exit, and returns its exit code. You need to use the traditional fork+exec approach.
With child PID available, it's easier to call kill(2) than kill(1)
Better add sleep in a dead loop waiting for input. This reduces CPU load and your electricity bill.
#include <stdio.h>
#include <signal.h>
#include <stdlib.h>
#include <unistd.h>
#include <sys/types.h>
pid_t child_id;
void ctrl_C(int sig){
kill(child_id, 9);
printf("\n You pressed Ctrl + C,Good Bye \n");
exit(0);
}
int main(){
printf("I am Programmer \n");
pid_t child_id = fork();
if (child_id == 0) {
execlp("gnome-terminal", "gnome-terminal", "--", "vi", "abcd.txt", NULL);
return 255;
}
signal(SIGINT,ctrl_C);
while (1) {
sleep(1);
}
}