#C++

The MPI standard is provided in a C and C++ library, which can be linked to your program by using the MPI C++ compiler, mpicxx.

The first step is to create a simple C++ program, which we will call hello_mpi. Open a text editor (e.g. nano), create a file called hello_mpi.cpp and copy in the following code;

#include <iostream>

int main(int argc, char **argv)
{
    std::cout << "Hello MPI!\n";

    return 0;
}

You can compile this program using;

mpicxx hello_mpi.cpp -o hello_mpi

Note that the MPI C++ compiler mpicxx must be in your path. The compiler will be provided by the MPI library that you have installed. There are many different implementations of the MPI library, e.g. OpenMPI and mpich2. While you could compile an MPI program using your normal C++ compiler, the specifics of linking the program to the correct MPI library can be tricky. Each MPI library therefore provides mpicxx as a thin wrapper around your C++ compiler, that automates finding and linking to the right MPI library, and handling any MPI-specific command-line flags and additional dependencies.

If you cannot find mpicxx then you should either try to install an MPI library, or see if the library has been installed for you by your cluster administrator, e.g. it may have been installed as a module. At Bristol, we have OpenMPI installed as a module that can be loaded using the command;

module add openmpi/gcc

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