Sample MPI Program

mpi_sample.c

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

int 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, "Hello MPI World from process %d!", my_rank);
		dest = 0;
		/* use strlen+1 so that '\0' get transmitted */
		MPI_Send(message, strlen(message)+1, MPI_CHAR,
		   dest, tag, MPI_COMM_WORLD);
	}
	else{
		printf("Hello MPI World From process 0: Num processes: %d\n",p);
		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();


	return 0;
}