/* test of communication methods in MPI */ 

#include "mpi.h" 
#include <iostream.h> 
#include <string.h> 

int main(int argc, char **argv) 
{ 
   char buff[10];	// Buffer
   char *recv_buff;
   MPI_Status status;
   int nbytes;

   int numprocs; 
   int myid; 
   int i; 

   MPI_Init(&argc,&argv); 
   MPI_Comm_size(MPI_COMM_WORLD,&numprocs); 
   MPI_Comm_rank(MPI_COMM_WORLD,&myid); 

   if(myid == 0) 
   { 
      cout << "We have " << numprocs << " processors" << endl;

      MPI_Probe(MPI_ANY_SOURCE, MPI_ANY_TAG, MPI_COMM_WORLD, &status);

      // Allocate memory to receive data
      MPI_Get_count(&status, MPI_CHAR, &nbytes); 

      cout << "Received " 
	   << nbytes << " bytes from proc " 
	   << status.MPI_SOURCE << " with tag " 
	   << status.MPI_TAG << endl;

      if ( nbytes != MPI_UNDEFINED )    
         recv_buff = (char *) malloc( nbytes );

      MPI_Recv(recv_buff, nbytes, MPI_CHAR, status.MPI_SOURCE, status.MPI_TAG,
               MPI_COMM_WORLD, NULL);     

      cout << ">>>>> ";
      for ( i = 0; i < nbytes; i++ )
          cout << recv_buff[i];
      cout << endl;
   } 
   else  if ( myid == 1 )
   { 
      strcpy(buff, "Hello World");
      MPI_Send(&buff, 4, MPI_CHAR, 0, 0, MPI_COMM_WORLD); 
   }

   MPI_Finalize(); 
}