//
// nearly the simplest possible message-passing program:
//
// process 0 sends a message, and process 1 receives and prints it.
//

#include <stdio.h>
#include <stdlib.h>		// has exit(), etc.
#include "mpi++.h"		// MPI header file

int main(int argc, char *argv[]) {

  // initialize for MPI (should come before any other calls to
  //     MPI routines)
  MPI::Init(argc, argv);

  // get number of processes
  int nprocs = MPI::COMM_WORLD.Get_size();

  // get this process's number (ranges from 0 to nprocs - 1)
  int myid = MPI::COMM_WORLD.Get_rank();

  const int bufflen = 2;
  int buff[bufflen];
  int mytag = 0;

  if (myid == 0) {
    // in process 0:  send message to process 1
    buff[0] = 10;
    buff[1] = 20;
    int dest = 1;
    MPI::COMM_WORLD.Send(buff, bufflen, MPI::INTEGER, dest, mytag);
    cout << "process 0 sent " << buff[0] << " " << buff[1] << endl;
  }
  else {
    // in process 1:  receive message from process 0 and print
    MPI::Status status;
    int source = 0;
    MPI::COMM_WORLD.Recv(buff, bufflen, MPI::INTEGER, source, mytag,
			 status);
    cout << "process 1 received " << buff[0] << " " << buff[1] << endl;
  }

  // clean up for MPI 
  MPI::Finalize();

  return EXIT_SUCCESS;
}