#include <stddef.h>
#include <stdlib.h>
#include "mpi.h"

/* MPI Send and Recv Example */

int main(int argc, char **argv )
{
  char message[20];
  int i, rank, size, tag=0;
  MPI_Status status;		/* MPI pre-defined status struc */ 

  MPI_Init(&argc, &argv);
  MPI_Comm_size(MPI_COMM_WORLD, &size);
  MPI_Comm_rank(MPI_COMM_WORLD, &rank);

  strcpy(message, "Empty");	/* Initialize the string array */

  if(rank == 0) {

    printf("Welcome to MPI\n");
    printf("The number of processes :: %d\n", size);
    strcpy(message, "Hello, world");	/* Root overwrites its string array */
 
    for (i=1; i<size; i++){ 		/* Root sends out its new msg to other processes */
      MPI_Send(message, 20, MPI_CHAR, i, tag, MPI_COMM_WORLD);
    }

  } else { 				/* Other processes receive the new msg */
    MPI_Recv(message, 20, MPI_CHAR, 0, tag, MPI_COMM_WORLD, &status);
  }

  printf( "Greeting from process ID :: %d\t%s\n", rank, message);

  MPI_Finalize();

  return 0;
}