Learning to fork() idle processes in C++

Question

Here's a revision of my programming problem:

1. Fork off two idle processes that run for a random time, each one running between 0 - 20 seconds.
2. Processes should use signals SIGSTOP and SIGCONT to schedule the processes in a round-robin queue.
3. When the child processes BOTH terminate for each idle process, the parent should terminate as well.
4. If one of the child processes terminate, it should keep going, until both of them are terminated using SIGCHLD.

This is about how far I'm at.

#include <iostream>
#include <unistd.h>
#include <sys/wait.h>

using namespace std;
using std::cout;

volatile sig_atomic_t keep_going = 1;

void catch_child (int sig)
{ int status, p;
  p = waitpid(-1,&status,WNOHANG);
  if (p==0) return;
  keep_going=0;
  cout<<"Child process caught: "<< p <<endl;
  return;
}


int  main()
{
  pid_t pid;
  pid_t mypid;
  int rand1;

  rand1 = rand()%20;    

  signal (SIGCHLD, catch_child);

  pid = fork();
  if (pid<0) {
    cout<<"Error\n";
    return 0;
  }
  else if (pid==0) {


    mypid = getpid();
    cout << "Child pid is " << mypid << "\n";
    execlp("./idle","./idle","1",rand1,0);
  } else {
    mypid=getpid();

    cout<<"parent procss is "<<mypid<<" and child is "<<pid<<"\n";
    sleep(5);

    cout<<"pausing child "<<pid<<" for 5 seconds\n";
    kill(pid,SIGSTOP);

    for (int i=0; i<5; i++) sleep(1);

    cout<<"Resuming child "<<pid<<"\n";
    kill(pid,SIGCONT);

    cout<<"Parent process pid is "<<mypid<<" waiting for child to stop\n";
    while (keep_going==1) sleep(1);
    // wait(NULL);


    cout <<"Parent knows that Child now done\n";
  }
  return 0;
}