hello-world.c

#include <stdio.h>
#include <mpi.h>
int main (int argc, char** args) {
    int size;
    int myrank;
    MPI_Init(&argc, &args);
    MPI_Comm_size(MPI_COMM_WORLD, &size);
    MPI_Comm_rank(MPI_COMM_WORLD, &myrank);
    printf("Hello world, I have rank %d out of %d.\n",
        myrank, size);
    MPI_Finalize();
    return 0;
}