NAME

MPI_Type_commit - Commits a data type.

SYNTAX

C Syntax

#include <mpi.h>
int MPI_Type_commit(MPI_Datatype *datatype)

Fortran Syntax

USE MPI
! or the older form: INCLUDE 'mpif.h'
MPI_TYPE_COMMIT(DATATYPE, IERROR)
	INTEGER	DATATYPE, IERROR

C++ Syntax

#include <mpi.h>
void Datatype::Commit()

INPUT PARAMETER

datatype

Data type (handle).

OUTPUT PARAMETER

IERROR

Fortran only: Error status (integer).

DESCRIPTION

The commit operation commits the data type. A data type is the formal description of a communication buffer, not the content of that buffer. After a data type has been committed, it can be repeatedly reused to communicate the changing content of a buffer or, indeed, the content of different buffers, with different starting addresses.

Example: The following Fortran code fragment gives examples of using MPI_Type_commit.

    INTEGER type1, type2


    CALL MPI_TYPE_CONTIGUOUS(5, MPI_REAL, type1, ierr)


                  ! new type object created


    CALL MPI_TYPE_COMMIT(type1, ierr)


                  ! now type1 can be used for communication

If the data type specified in datatype is already committed, it is equivalent to a no-op.

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.