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MPI_Comm_get_attr(3OpenMPI)                                                      MPI_Comm_get_attr(3OpenMPI)



NAME
       MPI_Comm_get_attr - Retrieves attribute value by key.


SYNTAX
C Syntax
       #include <mpi.h>
       int MPI_Comm_get_attr(MPI_Comm comm, int comm_keyval,
            void *attribute_val, int *flag)


Fortran Syntax (see FORTRAN 77 NOTES)
       INCLUDE 'mpif.h'
       MPI_COMM_GET_ATTR(COMM, COMM_KEYVAL, ATTRIBUTE_VAL, IERROR)
            INTEGER   COMM, COMM_KEYVAL, IERROR
            INTEGER(KIND=MPI_ADDRESS_KIND) ATTRIBUTE_VAL
            LOGICAL FLAG


C++ Syntax
       #include <mpi.h>
       bool MPI::Comm::Get_attr(int comm_keyval, void* attribute_val)
            const


INPUT PARAMETERS
       comm      Communicator to which the attribute is attached (handle).

       comm_keyval
                 Key value (integer).


OUTPUT PARAMETER
       attribute_val
                 Attribute value, unless flag = false.

       flag      False if no attribute is associated with the key (logical).

       IERROR    Fortran only: Error status (integer).


DESCRIPTION
       MPI_Comm_get_attr  retrieves an attribute value by key. The call is erroneous if there is no key with
       value keyval. On the other hand, the call is correct if the key value exists,  but  no  attribute  is
       attached  on  comm for that key; in that case, the call returns flag = false. In particular, MPI_KEY-VAL_INVALID MPI_KEYVAL_INVALID
       VAL_INVALID is an erroneous key value.

       This function replaces MPI_Attr_get, the use of which is deprecated. The C binding is identical.  The
       Fortran binding differs in that attribute_val is an address-sized integer.


FORTRAN 77 NOTES
       The  MPI  standard prescribes portable Fortran syntax for the ATTRIBUTE_VAL argument only for Fortran
       90. Sun FORTRAN 77 users may use the non-portable syntax

            INTEGER*MPI_ADDRESS_KIND ATTRIBUTE_VAL

       where MPI_ADDRESS_KIND is a constant defined in mpif.h and gives the length of the  declared  integer
       in bytes.


ERRORS
       Almost  all  MPI  routines return an error value; C routines as the value of the function and Fortran
       routines in the last argument. C++ functions do not return errors. If the default  error  handler  is
       set  to MPI::ERRORS_THROW_EXCEPTIONS, then on error the C++ exception mechanism will be used to throw
       an MPI:Exception object.

       Before the error value is returned, the current MPI error handler is called. By default,  this  error
       handler  aborts  the  MPI  job, except for I/O function errors. The error handler may be changed with
       MPI_Comm_set_errhandler; the predefined error handler MPI_ERRORS_RETURN may be used  to  cause  error
       values  to  be  returned.  Note  that MPI does not guarantee that an MPI program can continue past an
       error.




Open MPI 1.2                                   September 2006                    MPI_Comm_get_attr(3OpenMPI)