11.cpp

10 Mpi source examples for begginers

#include <mpi.h>
#include <stdio.h>
#include <stdlib.h>

#define DIM 5

int main(int argc, char** argv)
{
	MPI_Init(&argc, &argv);

	int One[DIM];
	int Two[DIM];
	int size, rank;
	int  *b1;
	int  *b2;
	MPI_Status status;
	b1=(int*)malloc(sizeof(int)*DIM);
	b2=(int*)malloc(sizeof(int)*DIM);
	MPI_Comm_size(MPI_COMM_WORLD, &size);
	MPI_Comm_rank(MPI_COMM_WORLD, &rank);

	for (int i=0; i<DIM; i++)
			One[i]=rank+rand()%10;

	printf("\nOriginal row : %d == ", rank);
	for (int j=0; j<DIM; j++)
		printf("%d ", One[j]);
	printf("\n");
	int pos = 0;
	int len = sizeof(int)*DIM;
	
	MPI_Pack(&One, DIM, MPI_INT, b1, len, &pos, MPI_COMM_WORLD);
	MPI_Sendrecv(b1, len, MPI_PACKED, size-rank-1, 1, b2, len, MPI_PACKED, size-rank-1, 1, MPI_COMM_WORLD, &status); 
	pos=0;
	MPI_Unpack(b2, len, &pos, &Two, DIM, MPI_INT, MPI_COMM_WORLD);
	//
	printf("New_________ : %d == ", rank);
	for (int j=0; j<DIM; j++)
		printf("%d ", Two[j]);
	printf("\n");
	free(b1);
	free(b2);
	MPI_Finalize();
}