SYNTAX

   C Syntax
          #include <mpi.h>

          int MPI_File_get_type_extent(MPI_File fh, MPI_Datatype
               datatype, MPI_Aint *extent)

   Fortran Syntax
          USE MPI
          ! or the older form: INCLUDE 'mpif.h'
          MPI_FILE_GET_TYPE_EXTENT(FH, DATATYPE, EXTENT, IERROR)
               INTEGER FH, DATATYPE, IERROR
               INTEGER(KIND=MPI_ADDRESS_KIND)  EXTENT

   Fortran 2008 Syntax
          USE mpi_f08
          MPI_File_get_type_extent(fh, datatype, extent, ierror)
               TYPE(MPI_File), INTENT(IN) :: fh
               TYPE(MPI_Datatype), INTENT(IN) :: datatype
               INTEGER(KIND=MPI_ADDRESS_KIND), INTENT(OUT) :: extent
               INTEGER, OPTIONAL, INTENT(OUT) :: ierror

INPUT PARAMETERS

       • fh: File handle (handle).

       • datatype: Data type (handle).

OUTPUT PARAMETERS

       • extent: Data type extent (integer).

       • ierror: Fortran only: Error status (integer).

DESCRIPTION

       MPI_File_get_type_extent can be used to calculate extent for datatype in the file. The extent is the same
       for  all  processes  accessing  the file associated with fh. If the current view uses a user-defined data
       representation, MPI_File_get_type_extent uses the dtype_file_extent_fn callback to calculate the extent.

NOTES

       If the file data representation is other than “native,” care must be taken  in  constructing  etypes  and
       file  types.  Any  of  the data-type constructor functions may be used; however, for those functions that
       accept displacements in bytes, the displacements must be specified in terms of their values in  the  file
       for  the  file  data  representation  being  used.  MPI will interpret these byte displacements as is; no
       scaling will be done. The function MPI_File_get_type_extent can be used to calculate the extents of  data
       types  in  the  file.  For  etypes  and  file  types  that  are  portable  data types, MPI will scale any
       displacements in the data types to match the file data representation. Data types passed as arguments  to
       read/write  routines  specify the data layout in memory; therefore, they must always be constructed using
       displacements corresponding to displacements in memory.

ERRORS

       Almost all MPI routines return an error value; C routines as  the  return  result  of  the  function  and
       Fortran routines in the last argument.

       Before  the  error  value  is  returned,  the current MPI error handler associated with the communication
       object (e.g., communicator, window, file) is called.  If no communication object is associated  with  the
       MPI  call,  then  the call is considered attached to MPI_COMM_SELF and will call the associated MPI error
       handler.  When  MPI_COMM_SELF  is  not  initialized   (i.e.,   before   MPI_Init/MPI_Init_thread,   after
       MPI_Finalize,  or  when using the Sessions Model exclusively) the error raises the initial error handler.
       The initial error handler can be changed by calling MPI_Comm_set_errhandler on MPI_COMM_SELF  when  using
       the  World  model,  or the mpi_initial_errhandler CLI argument to mpiexec or info key to MPI_Comm_spawn/‐
       MPI_Comm_spawn_multiple.  If no other appropriate error handler has been set, then the  MPI_ERRORS_RETURN
       error  handler  is  called for MPI I/O functions and the MPI_ERRORS_ABORT error handler is called for all
       other MPI functions.

       Open MPI includes three predefined error handlers that can be used:

       • MPI_ERRORS_ARE_FATAL Causes the program to abort all connected MPI processes.

       • MPI_ERRORS_ABORT An error handler that can be invoked on a communicator, window, file, or session. When
         called on a communicator, it acts as if MPI_Abort was called on  that  communicator.  If  called  on  a
         window  or file, acts as if MPI_Abort was called on a communicator containing the group of processes in
         the corresponding window or file. If called on a session, aborts only the local process.

       • MPI_ERRORS_RETURN Returns an error code to the application.

       MPI applications can also implement their own error handlers by calling:

       • MPI_Comm_create_errhandler then MPI_Comm_set_errhandler

       • MPI_File_create_errhandler then MPI_File_set_errhandler

       • MPI_Session_create_errhandler then MPI_Session_set_errhandler or at MPI_Session_init

       • MPI_Win_create_errhandler then MPI_Win_set_errhandler

       Note that MPI does not guarantee that an MPI program can continue past an error.

       See the MPI man page for a full list of MPI error codes.

       See the Error Handling section of the MPI-3.1 standard for more information.

COPYRIGHT

       2003-2025, The Open MPI Community

                                                  Feb 17, 2025                       MPI_FILE_GET_TYPE_EXTENT(3)