hello_mpi.cpp

// 'Hello World!' program 
 
#include <iostream>
#include <mpi.h>

#include <memory>
 
struct Vec3
{
    int x, y, z;
    Vec3() : x(0), y(0), z(0) { }
    Vec3(int x, int y, int z) :x(x), y(y), z(z) { }
    friend std::ostream& operator<<(std::ostream& os, Vec3& v) {
        return os << '{' << "x:" << v.x << " y:" << v.y << " z:" << v.z  << '}';
    }
};
 
int main(int argc, char** argv)
{
    auto v = std::make_unique<Vec3>();
 
    MPI_Init(&argc, &argv);
    int rank, size;
    MPI_Comm_rank(MPI_COMM_WORLD, &rank);
    MPI_Comm_size(MPI_COMM_WORLD, &size);

    std::cout << " oh hello " << rank << " of " << size << std::endl;

    MPI_Finalize();
    
    return 0;
}