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MPI_Pack_size(3OpenMPI)                                                              MPI_Pack_size(3OpenMPI)



NAME
       MPI_Pack_size - Returns the upper bound on the amount of space needed to pack a message.


SYNTAX
C Syntax
       #include <mpi.h>
       int MPI_Pack_size(int incount, MPI_Datatype datatype, MPI_Comm comm,
            int *size)


Fortran Syntax
       INCLUDE 'mpif.h'
       MPI_PACK_SIZE(INCOUNT, DATATYPE, COMM, SIZE, IERROR)
            INTEGER   INCOUNT, DATATYPE, COMM, SIZE, IERROR


C++ Syntax
       #include <mpi.h>
       int Datatype::Pack_size(int incount, const Comm& comm) const


INPUT PARAMETERS
       incount   Count argument to packing call (integer).

       datatype  Datatype argument to packing call (handle).

       comm      Communicator argument to packing call (handle).


OUTPUT PARAMETERS
       size      Upper bound on size of packed message, in bytes (integer).

       IERROR    Fortran only: Error status (integer).


DESCRIPTION
       MPI_Pack_size  allows  the application to find out how much space is needed to pack a message. A call
       to MPI_Pack_size(incount, datatype, comm, size) returns in size an upper bound on  the  increment  in
       position  that  would  occur  in  a call to MPI_Pack, with the same values for incount, datatype, and
       comm.

       Rationale:  The call returns an upper bound, rather than an exact bound, since the  exact  amount  of
       space  needed  to pack the message may depend on the context (e.g., first message packed in a packing
       unit may take more space).


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.


SEE ALSO
       MPI_Pack
       MPI_Unpack





Open MPI 1.2                                   September 2006                        MPI_Pack_size(3OpenMPI)