How to correctly use the 'sleep()' system call in C

Question

I have been tasked with writing a C program which allows the child code to finish after the parent, using the sleep command.

This is what I have written, the code does not work and it only returns the 'else' part of the code. If anyone could help it would be much appreciated. I believe the problem is how I have used the sleep command.

#include <stdio.h>
#include <unistd.h>

int main() {
fork();
if (fork() ==0){
    sleep(5);
    printf("This will finish after the parent\n");
}
else
    printf("This will finish before the child\n");

return 0;
}

Answer 1

try to use the pid instead of fork() twice

#include <stdio.h>
    #include <unistd.h>
    
    int main() {
    pid_t pid=fork();
    if (pid==0){
        sleep(5);
        printf("This will finish after the parent\n");
    }
    else
        printf("This will finish before the child\n");
    
    return 0;
    }

Answer 2

This is what I came up with, but it is somewhat hard to tell which is the child class and the parent class.

int main() {
    fork();
    if (fork() ==0){
        // sleep(5);
        printf("This will finish after the parent\n");
    }
    else
    {
    sleep(5);
    printf("This will finish before the child\n");
    
    }
    return 0;
}

Answer 3

Fork system call is used for creating a new process.parent process and child process.the child get pid==0,but the parent get pid==(to the main pid of the child).

#include <stdio.h>
    #include <unistd.h>
    
    int main() {
    pid_t pid=fork();
    if (pid==0){
        sleep(5);
        printf("This will finish after the parent\n");
        printf("child pid is %d\n",getpid());//get the current process pid 
    }
    else
    {
        printf("This will finish before the child\n");
    printf("child pid is %d\n",pid);
    }
    return 0;
    }