.. _mpi_file_iwrite_at_all:


MPI_File_iwrite_at_all
======================

.. include_body

:ref:`MPI_File_iwrite_at_all` |mdash| Writes a file at an explicitly specified
offset (nonblocking, collective).

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.. include:: ./bindings/mpi_file_iwrite_at_all.rst

INPUT/OUTPUT PARAMETER
----------------------
* ``fh``: File handle (handle).

INPUT PARAMETERS
----------------
* ``offset``: File offset (integer).
* ``buf``: Initial address of buffer (choice).
* ``count``: Number of elements in buffer (integer).
* ``datatype``: Data type of each buffer element (handle).

OUTPUT PARAMETERS
-----------------
* ``request``: Request object (handle).
* ``ierror``: Fortran only: Error status (integer).

DESCRIPTION
-----------

:ref:`MPI_File_iwrite_at_all` is a nonblocking version of
:ref:`MPI_File_write_at_all`. It attempts to write into the file associated
with *fh* (at the *offset* position) a total number of *count* data
items having *datatype* type from the user's buffer *buf.* The offset is
in *etype* units relative to the current view. That is, holes are not
counted when locating an offset. The data is written into those parts of
the file specified by the current view. :ref:`MPI_File_iwrite_at_all` stores
the number of *datatype* elements actually written in *status.* All
other fields of *status* are undefined. The request structure can be
passed to :ref:`MPI_Wait` or :ref:`MPI_Test`, which will return a status with the
number of bytes actually accessed.

It is erroneous to call this function if ``MPI_MODE_SEQUENTIAL`` mode was
specified when the file was open.


ERRORS
------

.. include:: ./ERRORS.rst