MPI_FILE_GET_TYPE_EXTENT(3)			     Open MPI			       MPI_FILE_GET_TYPE_EXTENT(3)

MPI_File_get_type_extent — Returns the extent of the data type in a file.

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>/MPI_Init_thread  <#mpi-init-thread>,
       after  MPI_Finalize  <#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	<#
       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>/MPI_Comm_spawn_multiple	<#
       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 <#mpi-abort> was called on that communicator. If called
	 on a window or file, acts as if MPI_Abort <#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	 <#mpi-comm-create-errhandler>	   then	    MPI_Comm_set_errhandler	<#
	 mpi-comm-set-errhandler>

       • MPI_File_create_errhandler	<#mpi-file-create-errhandler>	  then	   MPI_File_set_errhandler	<#
	 mpi-file-set-errhandler>

       • MPI_Session_create_errhandler	 <#mpi-session-create-errhandler>   then   MPI_Session_set_errhandler	<#
	 mpi-session-set-errhandler> or at MPI_Session_init <#mpi-session-init>

       • MPI_Win_create_errhandler	<#mpi-win-create-errhandler>	  then	    MPI_Win_set_errhandler	<#
	 mpi-win-set-errhandler>

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

       See the MPI man page <#open-mpi> for a full list of MPI error codes <#open-mpi-errors>.

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

Copyright
       2003-2026, The Open MPI Community

						   Mar 05, 2026			       MPI_FILE_GET_TYPE_EXTENT(3)
