// Fork.cpp
//  Working with UNIX processes: To compile and run:
//    g++ fork.cpp -o fork 
//    chmod u+x fork
//    ./fork
//    ./fork > fork.out
//
#include <sys/types.h>  // defines pid_t
#include <unistd.h>	// defines fork
#include <iostream>	// defines cout, cin
#include <stdlib.h>     // defines exit()
#include <sys/wait.h>   // defines wait()
using namespace std;

class Process {
public:
   Process()    {} 
   int laugh(int sleep_time,char* text);
private:
};

int Process::laugh(int sleep_time, char* text)
{
      // Get process ID
      pid_t  identification = getpid();

      // Print text 5000 times in rows of 10
      for (int i=0; i<500000; i++) {
            if (sleep_time > 0) sleep (sleep_time);
            cout << text << " "; 
	    if (i%10==0) cout << endl;
      }

      // Print that process is done - with its ID
      cout << "Completed: " << identification << endl;
      exit(0);   // do not return
}

int main()
{
      Process child;
      int stat;        // returns a status from the child here
      int sleep_time;
      char Ha[] = "Ha!";
      char Ho[] = "Ho!";
      char He[] = "He!";

      // get time to sleep
      cerr << "sleep_time (-1 to +3): ";
      cin >> sleep_time;

      // Create children
      if (fork() == 0)  // child process
         child.laugh(sleep_time,Ha);  
      if (fork() == 0)  // child process
         child.laugh(sleep_time,Ho);  
      if (fork() == 0)  // child process
         child.laugh(sleep_time,He);  
      // Have parent pause to wait for all children to complete before terminating
      //wait(&stat);
      //wait(&stat);
      //wait(&stat);
      // sleep(10);    // Sleep 10 seconds if wait() does not work
      cout << "All done" << endl;
}