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

using std::cout;
using std::endl;

int main(int argc, char* argv[])
{
  MPI::Init(argc, argv);
  
  const int size = MPI::COMM_WORLD.Get_size();
  if (size != 2) return MPI::ERR_SIZE;  //check for 2 processes

  const int rank = MPI::COMM_WORLD.Get_rank();

  if (rank==0)  //the sender
  {
    double toSend = 13.13;
    const int cnt = 1;
    const int dest = 1;
    const int tag = 0;

    cout << "process " << rank << " sends "<< toSend << " to process " << dest << endl;
    MPI::COMM_WORLD.Send(&toSend, cnt, MPI::DOUBLE, dest, tag);
  }
  else  //the receiver
  {
    double toRecv;
    const int cnt = 1;
    const int from = 0;
    const int tag = 0;  

    MPI::COMM_WORLD.Recv(&toRecv, cnt, MPI::DOUBLE, from, tag);  
    cout << "process " << rank << " received "<< toRecv << " from process " << from << endl;
  }
  MPI::Finalize();  
}