OpenMPI

main.cc

#include <iostream>
#include <mpi.h>

using namespace std;

void send (int data, int toProcess) {
  MPI_Send(
    &data,
    1,
    MPI_INT,
    toProcess,
    0,
    MPI_COMM_WORLD);
}

void receive (int* data, int fromProcess) {
  MPI_Recv(
    data,
    1,
    MPI_INT,
    fromProcess,
    0,
    MPI_COMM_WORLD,
    MPI_STATUS_IGNORE);
}

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

  int size = 0;
  MPI_Comm_size(MPI_COMM_WORLD, &size);
  // cout << size << endl;

  int rank = 0;
  MPI_Comm_rank(MPI_COMM_WORLD, &rank);
  cout << "Rank: " << rank << endl;

  int number = 0;
  if (!(rank % 2)) {
    number = rank;

    send(number, rank + 1);

    cout << "Process " << rank << " sent " << number << endl;
  } else {
    receive(&number, rank - 1);

    cout << "Process " << rank << " received " << number << endl;
  }

  MPI_Finalize();
}

Makefile

all: main.out
	mpirun -n 4 ./$<

main.out: main.o
	mpic++ -o $@ $<

main.o: main.cc
	mpic++ -c -o $@ $<

clean:
	rm main.o
	rm main.out