afork.c

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

void ChildProcess(void);
void ParentProcess(void);
int pid;
int i;
int parent_pid;
int child_pid;
int the_pid;
int main(void)
{
    parent_pid=getpid();
    child_pid=fork(); /*Returns child_pid to parent*/
    if (getpid()==parent_pid) {
        printf("\nIn the parent: parent %d - child %d\n",parent_pid,child_pid);
    } else {
        printf("\nBefore child getting its getpid(): parent %d - child %d\n",parent_pid,child_pid);
        child_pid=getpid();
        printf("After child getting its getpid(): parent %d - child %d\n\n",parent_pid,child_pid);
    }
    if (getpid()==child_pid) {
        ChildProcess();
    } else {
        ParentProcess();
    }
    return 0;
}

void ChildProcess(void)
{
    while (i<6) {
        printf ("The child with pid %d is doing some work and the present value of i=%d\n", getpid(),i);
        i++;
        sleep(3);
    }
}

void ParentProcess(void)
{
    while (i<6) {
        printf ("The parent with pid %d is doing some work and the present value of i=%d\n", getpid(),i);
        i++;
        sleep(1);

    }
}

I had to stop the child in the command window.