How to print PID of grand child in parent without using pipe? How to count number of child processes and grand child processes?

Write a C program to create a child process using the system call fork( ). From the child process, display
the PID and PPID and then call again the fork( ) to create a grandchild and engage him to display your roll
no. From parent display the PID and PPID of all the processes and display the count of total no. of child
processes created also the number of grandchild processes created. Demonstrate the use of exit(0) and
exit(1).

I tried this piece of code

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

int main()
{
    FILE *fpPID = fopen("PIDs.txt", "w");
    fclose(fpPID);
    __pid_t child_pid = fork();

    if (child_pid < 0)
    {
        printf("Failed to create child process");
        exit(-1);
    }
    else if (child_pid == 0)
    {
        __pid_t grandChild_pid = fork();
        if (grandChild_pid < 0)
        {
            printf("Failed to create grandchild process");
            exit(-1);
        }
        else if (grandChild_pid == 0)
        {
            FILE *fpPID = fopen("PIDs.txt", "a");
            fprintf(fpPID, "%d\n", getpid());
            fclose(fpPID);

            printf("GRANDCHILD: CSM21009\n");
            exit(0);
        }
        else
        {
            printf("CHILD: PID: %d, PPID: %d \n", getpid(), getppid());
        }
    }
    else
    {
        sleep(1);
        int GrandChildPID;
        FILE *fpPID = fopen("PIDs.txt", "r");
        fscanf(fpPID, "%d", &GrandChildPID);
        fclose(fpPID);

        printf("PARENT: PID: %d, PPID: %d \n", getpid(), getppid());
        printf("PARENT: Child PID: %d, Child PPID: %d \n", child_pid, getpid());
        printf("PARENT: Grand Child PID: %d, Grand Child PPID: %d \n", GrandChildPID, child_pid);
        printf("number of Child = 1\n");
        printf("number of GrandChild = 1 \n");
        exit(0);
    }
}

Your code looks good overall, but there are a few improvements that can be made to ensure that the child and grandchild processes exit correctly and to properly count the number of child and grandchild processes. Here is the revised code:

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

int main()
{
    int child_count = 0, grandchild_count = 0;
    pid_t child_pid = fork();

    if (child_pid < 0)
    {
        printf("Failed to create child process");
        exit(-1);
    }
    else if (child_pid == 0)
    {
        child_count++;
        printf("CHILD: PID: %d, PPID: %d\n", getpid(), getppid());
        
        pid_t grandchild_pid = fork();
        if (grandchild_pid < 0)
        {
            printf("Failed to create grandchild process");
            exit(-1);
        }
        else if (grandchild_pid == 0)
        {
            grandchild_count++;
            printf("GRANDCHILD: CSM21009\n");
            printf("GRANDCHILD: PID: %d, PPID: %d\n", getpid(), getppid());
            exit(0);
        }
        else
        {
            int status;
            waitpid(grandchild_pid, &status, 0);
            exit(0);
        }
    }
    else
    {
        int status;
        waitpid(child_pid, &status, 0);

        printf("PARENT: PID: %d, PPID: %d\n", getpid(), getppid());
        printf("


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