/* 

   example2
   
   note: iostream is not thread-safe. cout calls must be executed in
   critical areas or by only one thread.
   
   What it does: forks a number of threads; each thread prints its
   thread-id. They all wait at a barrier.  then the master prints the
   number of threads.
   
*/ 

#include <iostream>
#include <omp.h>

int main() {


  int th_id, nthreads;


#pragma omp parallel private(th_id) shared(nthreads)
  /* 
     th_id and nthreads are declared above.  th_id is private to each
     thread, and nthreads is shared
   */ 
  {
    th_id = omp_get_thread_num();

#pragma omp critical
    //this block is specified as critical, meaning its executed by one
    //thread at a time
    {
      std::cout << "Hello World from thread " << th_id << '\n';
    }

#pragma omp barrier
    //each thread waits until all other threads have reached this point  
    
#pragma omp master
    //this block is specified as master, meaning its executed only by
    //the master thread
    {
      nthreads = omp_get_num_threads();
      std::cout << "There are " << nthreads << " threads" << '\n';
    }
  }

  return 0;
}