Example 1: Hello world!

In this example, we show how to implement the standard Hello world program using mpi.

#include <mpi/mpi.hpp>
#include <iostream>
 
int main(int argc, char *argv[]) {
  // initialize MPI environment and communicator
  mpi::environment env(argc, argv);
  mpi::communicator world;
 
  // get rank and greet world
  int rank = world.rank();
  std::cout << "Hello from processor " << rank << "\n";
}

Output (depends on the number of processes and the order is arbitrary):

Hello from processor 2
Hello from processor 3
Hello from processor 0
Hello from processor 1