/* 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; and CC Bordeianu, Univ Bucharest, 2007.
   Support by National Science Foundation                              
   */
// Code listing for MPIdeadlock.c
#include <stdio.h>
#include "mpi.h"
#define MAXLEN 100
main(int argc, char *argv[]) {
	
    int myrank, numprocs, fromrank, torank;
    char tosend[MAXLEN], received[MAXLEN];
    MPI_Status status;
    MPI_Init(&argc,&argv);
    MPI_Comm_rank(MPI_COMM_WORLD,&myrank);
    MPI_Comm_size(MPI_COMM_WORLD,&numprocs);
    if (myrank == 0) fromrank = numprocs - 1;
    else fromrank = myrank - 1;
    if (myrank == numprocs - 1) torank = 0;
    else torank = myrank + 1;
    // Save string to send in tosend:
    sprintf(tosend,"Message from node %d to %d\n", myrank,torank);
    MPI_Recv(received,MAXLEN,MPI_CHAR,fromrank,0,MPI_COMM_WORLD,
                                       &status);
    MPI_Send(tosend,MAXLEN,MPI_CHAR,torank,0,MPI_COMM_WORLD);
    printf("%s",received);   // Print string after successful receive
    MPI_Finalize();
    exit(0);
}