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MPI_Comm_get_name.3.rst

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MPI_Comm_get_name

:ref:`MPI_Comm_get_name` |mdash| Returns the name that was most recently associated with a communicator.

SYNTAX

C Syntax

#include <mpi.h>

int MPI_Comm_get_name(MPI_Comm comm, char *comm_name, int *resultlen)

Fortran Syntax

USE MPI
! or the older form: INCLUDE 'mpif.h'
MPI_COMM_GET_NAME(COMM, COMM_NAME, RESULTLEN, IERROR)
     INTEGER COMM, RESULTLEN, IERROR
     CHARACTER*(*) COMM_NAME

Fortran 2008 Syntax

USE mpi_f08
MPI_Comm_get_name(comm, comm_name, resultlen, ierror)
     TYPE(MPI_Comm), INTENT(IN) :: comm
     CHARACTER(LEN=MPI_MAX_OBJECT_NAME), INTENT(OUT) :: comm_name
     INTEGER, INTENT(OUT) :: resultlen
     INTEGER, OPTIONAL, INTENT(OUT) :: ierror

INPUT PARAMETER

  • comm: Communicator the name of which is to be returned (handle).

OUTPUT PARAMETER

  • comm_name: Name previously stored on the communicator, or an empty string if no such name exists (string).
  • resultlen: Length of returned name (integer).
  • ierror: Fortran only: Error status (integer).

DESCRIPTION

:ref:`MPI_Comm_get_name` returns the last name that was previously associated with the given communicator. The name may be set and retrieved from any language. The same name will be returned independent of the language used. comm_name should be allocated so that it can hold a resulting string of length MPI_MAX_OBJECT_NAME characters. :ref:`MPI_Comm_get_name` returns a copy of the set name in comm_name.

If the user has not associated a name with a communicator, or an error occurs, :ref:`MPI_Comm_get_name` will return an empty string (all spaces in Fortran, "" in C). The three predefined communicators will have predefined names associated with them. Thus, the names of MPI_COMM_WORLD, MPI_COMM_SELF, and MPI_COMM_PARENT will have the default of MPI_COMM_WORLD, MPI_COMM_SELF, and MPI_COMM_PARENT. The fact that the system may have chosen to give a default name to a communicator does not prevent the user from setting a name on the same communicator; doing this removes the old name and assigns the new one.

NOTES

It is safe simply to print the string returned by :ref:`MPI_Comm_get_name`, as it is always a valid string even if there was no name.

Note that associating a name with a communicator has no effect on the semantics of an MPI program, and will (necessarily) increase the store requirement of the program, since the names must be saved. Therefore, there is no requirement that users use these functions to associate names with communicators. However debugging and profiling MPI applications may be made easier if names are associated with communicators, since the debugger or profiler should then be able to present information in a less cryptic manner.

ERRORS