mpi_hello.cpp

// This program shows off the basics of using MPI with C++
// By: Nick from CoffeeBeforeArch

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

using namespace std;

int main(int argc, char *argv[]) {
  // Unique rank is assigned to each process in a communicator
  int rank;

  // Total number of ranks
  int size;

  // The machine we are on
  char name[80];

  // Length of the machine name
  int length;

  // Initializes the MPI execution environment
  MPI_Init(&argc, &argv);

  // Get this process' rank (process within a communicator)
  // MPI_COMM_WORLD is the default communicator
  MPI_Comm_rank(MPI_COMM_WORLD, &rank);

  // Get the total number ranks in this communicator
  MPI_Comm_size(MPI_COMM_WORLD, &size);

  // Gets the name of the processor
  // Implementation specific (may be gethostname, uname, or sysinfo)
  MPI_Get_processor_name(name, &length);

  // Print out for each rank
  cout << "Hello, MPI! Rank: " << rank << " Total: " << size
       << " Machine: " << name << endl;

  // Terminate MPI execution environment
  MPI_Finalize();

  return 0;
}