greetings.c

#include <stdio.h>

#include <string.h>

#include "mpi.h"

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

int my_rank; /* rank of process */

int p; /* number of processes */

int source; /* rank of sender */

int dest; /* rank of receiver */

int tag = 0; /* tag for messages */

char message[100]; /* storage for message */

MPI_Status status; /* return status for */

/* receive */

/* Start up MPI */

MPI_Init(&argc, &argv);

/* Find out process rank */

MPI_Comm_rank(MPI_COMM_WORLD, &my_rank);

/* Find out number of processes */

MPI_Comm_size(MPI_COMM_WORLD, &p);

if (my_rank != 0) {

/* Create message */

sprintf(message, "Greetings from process %d!",

my_rank);

dest = 0;

/* Use strlen+1 so that '\0' gets transmitted */

MPI_Send(message, strlen(message)+1, MPI_CHAR,

dest, tag, MPI_COMM_WORLD);

} else { /* my_rank == 0 */

for (source = 1; source < p; source++) {

MPI_Recv(message, 100, MPI_CHAR, source, tag,

MPI_COMM_WORLD, &status);

printf("%s\n", message);

}

}

/* Shut down MPI */

MPI_Finalize();

} /* main */

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