"Hello World!" Code Examples

Hello_World_C.c

#include <stdio.h>
#include <mpi.h>

main (int argc, char **argv)
{
 int node;

 MPI_Init(&argc, &argv);
 MPI_Comm_rank(MPI_COMM_WORLD, &node);

 if (node == 0) {
 printf("Rank 0 is present in C version of Hello World.\n");
 } else {
 printf("  Rank %d of C version says: Hello world!\n", node);
 }

 MPI_Finalize();
}

Hello_World_Fortran.f90

PROGRAM Hello_World_Fortran

IMPLICIT NONE
INCLUDE 'mpif.h'

INTEGER :: ierr_p, rank_p, size_p
INTEGER :: status_p(MPI_STATUS_SIZE)

CALL MPI_INIT(ierr_p)
CALL MPI_COMM_RANK(MPI_COMM_WORLD, rank_p, ierr_p)
CALL MPI_COMM_SIZE(MPI_COMM_WORLD, size_p, ierr_p)

IF (rank_p==0) THEN
WRITE(*,*) 'Rank 0 is present in Fortran version of Hello World.'
ELSE
WRITE(*,*) 'Fortran version of Hello World, rank ', rank_p
END IF

CALL MPI_FINALIZE(ierr_p)

END PROGRAM Hello_World_Fortran