[OMPI users] question about passing MPI communicator

[Wang, Peng]

Hello, I am wondering in openmpi how is the passing of MPI communcator 
from Fortran to C is handled? Assuming I have a Fortran 90 subroutine 
calling a C function passing MPI_COMM_WORLD in, in the C function, do I 
need to first do MPI_Comm_f2c
to convert to MPI handle, then use that handle afterward? Or is there 
any better way to do this? Here is some test code:

Fortran 90:
       program test1

       include 'mpif.h'

       integer myrank,ierr

       call MPI_Init(ierr)

       call parallel_info(myrank,MPI_COMM_WORLD)
       write(*,*) 'hello, I am process #',myrank

       call MPI_Finalize(ierr)

       end program test1


C:

#include <mpi.h>

void parallel_info_(int * rank, int* comm)
{
   MPI_Comm ccomm;

   ccomm=MPI_Comm_f2c(*comm);
   MPI_Comm_rank(ccomm, rank);
}

void parallel_info(int * rank, int * comm)
{
   MPI_Comm ccomm;

   ccomm=MPI_Comm_f2c(*comm);

   MPI_Comm_rank(ccomm, rank);
}


Thanks,
Peng