/* From: "COMPUTATIONAL PHYSICS, 2nd Ed" 
   by RH Landau, MJ Paez, and CC Bordeianu 
   Copyright Wiley-VCH 2007.
   Electronic Materials copyright: R Landau, Oregon State Univ, 2007;
   MJ Paez, Univ Antioquia, 2007; & CC Bordeianu, Univ Bucharest, 2007
   Support by National Science Foundation                              
*/  
//  MPImessage2.c:  source node sends message to dest

#include "mpi.h"
#include <stdio.h>

int main(int argc,char *argv[])  {   
	
  int rank;
  int msg_size = 6;
  MPI_Status status;
  int tag = 10;
  int source = 0, dest = 1;
  MPI_Init(&argc,&argv);                            // Initialize MPI
  MPI_Comm_rank(MPI_COMM_WORLD,&rank);              // Get CPU's rank
  if (rank == source) { 
    char *msg = "Hello";
    printf("Host about to send message: %s\n",msg);
                // Send message, may block till dest recieves message 
    MPI_Send(msg, msg_size, MPI_CHAR, dest, tag, MPI_COMM_WORLD); 
  }
    else if (rank == dest) { 
      char buffer[msg_size+1];
            // Receive message, may block till dest receieves message
      MPI_Recv( &buffer, msg_size, MPI_CHAR, source, tag,
                   MPI_COMM_WORLD, &status );
      printf("Message recieved by %d: %s\n", rank, buffer); 
    }
      printf("NODE %d done.\n", rank);            //  All nodes print
      MPI_Finalize();                                 // Finalize MPI
      return 0;
}