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MPI_Pack_size - Returns the packed size of a block of a type in bytes


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

#include <pmpi.h> int PMPI_Pack_size(int count , MPI_Datatype datatype , MPI_Comm comm , int *size );

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

INCLUDE 'mpif.h' MPI_PACK_SIZE(count , datatype , comm , size , ierr ) INTEGER count , datatype , comm , size , ierr


count - number of contiguous copies of type (integer)

datatype - type (handle)

comm - communicator that only affects which error handler is called (handle)


size - size of the packed data in bytes (integer).


The MPI_Pack_size() function is used to determine the size of a packed contiguous block of count copies of type datatype in bytes.

The C++ version of this function passes the size as the return value.

Even though the communicator, comm is not directly used by this function, it should be a valid one (not MPI_COMM_NULL).

PMPI_Pack_size() is the profiling version of this function.


All MPI routines except for MPI_Wtime and MPI_Wtick return an error code. The the current MPI error handler is invoked if the return value is not MPI_SUCCESS. The default error handler aborts, but this may be changed with by using the MPI_Errhandler_set() function. The predefined error handler MPI_ERRORS_RETURN may be used to cause error values to be returned instead. Note that MPI does not guarentee that an MPI program can continue past an error. In this implementation, all errors except MPI_ERR_INTERN or MPI_ERR_OTHER should always be recoverable.

In C, the error code is passed as the return value. In FORTRAN, all functions have an parameter ierr which returns the error code. MPI C++ functions do not directly return an error code. However, C++ users may want to use the MPI::ERRORS_THROW_EXCEPTIONS handler. This will throw an MPI::Exception with the corresponding error code. To prevent exceptions from being raised from within C and Fortran code, they will see all error return values as MPI_ERR_PENDING when this handler is chosen. In this implementation, call MPI::throw_exception() to throw the correct exception if this occurs.

MPI_SUCCESS - No error;

MPI_ERR_PENDING - Pending exception;

MPI_ERR_COMM - Invalid communicator;

MPI_ERR_TYPE - Invalid data type;

MPI_ERR_COUNT - Invalid count;

MPI_ERR_ARG - Invalid pointer.


MPI_Type_size (3) MPI_Pack (3) MPI_Unpack (3)

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