MPI_PACK_SIZE, MPI_Pack_size

Purpose

Returns the number of bytes required to hold the data.

C synopsis

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

C++ synopsis

#include mpi.h
int MPI::Datatype::Pack_size(int incount, const MPI::Comm& comm) const;

FORTRAN synopsis

include 'mpif.h' or use mpi
MPI_PACK_SIZE(INTEGER INCOUNT,INTEGER DATATYPE,INTEGER COMM,
              INTEGER SIZE,INTEGER IERROR)

Parameters

incount
     is an integer specifying the count argument to a packing call (IN)

datatype
     is the datatype argument to a packing call (handle) (IN)

comm
     is the communicator to a packing call (handle) (IN)

size
     is the size of packed message in bytes (integer) (OUT)

IERROR
     is the FORTRAN return code. It is always the last argument.

Description

This subroutine returns the number of bytes required to pack incount
replications of the datatype. You can use MPI_PACK_SIZE to determine the
size required for a packing buffer or to track space needed for buffered
sends.

Notes

MPI_PACK_SIZE must be used with some care in 64-bit applications because
the size argument is an integer and can be subject to overflow.

Errors

Invalid datatype

Type is not committed

MPI not initialized

MPI already finalized

Invalid communicator

Invalid incount
     incount < 0

Size overflow
     64-bit applications only

Related information