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MPI_File_iread.3.rst

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MPI_File_iread

:ref:`MPI_File_iread` - Reads a file starting at the location specified by the individual file pointer (nonblocking, noncollective).

SYNTAX

C Syntax

#include <mpi.h>

int MPI_File_iread(MPI_File fh, void  *buf, int  count,
     MPI_Datatype  datatype, MPI_Request  *request)

Fortran Syntax

USE MPI
! or the older form: INCLUDE 'mpif.h'
MPI_FILE_IREAD(FH, BUF, COUNT, DATATYPE, REQUEST, IERROR)
     <type>  BUF(*)
     INTEGER FH, COUNT, DATATYPE, REQUEST, IERROR

Fortran 2008 Syntax

USE mpi_f08
MPI_File_iread(fh, buf, count, datatype, request, ierror)
     TYPE(MPI_File), INTENT(IN) :: fh
     TYPE(*), DIMENSION(..), ASYNCHRONOUS :: buf
     INTEGER, INTENT(IN) :: count
     TYPE(MPI_Datatype), INTENT(IN) :: datatype
     TYPE(MPI_Request), INTENT(OUT) :: request
     INTEGER, OPTIONAL, INTENT(OUT) :: ierror

INPUT/OUTPUT PARAMETER

  • fh: File handle (handle).

INPUT PARAMETERS

  • count: Number of elements in the buffer (integer).
  • datatype: Data type of each buffer element (handle).

OUTPUT PARAMETERS

  • buf: Initial address of buffer (choice).
  • request: Request object (handle).
  • ierror: Fortran only: Error status (integer).

DESCRIPTION

:ref:`MPI_File_iread` is a nonblocking version of :ref:`MPI_File_read`. It attempts to read from the file associated with fh at the current individual file pointer position maintained by the system in which a total number of count data items having datatype type are read into the user's buffer buf. The data is taken out of those parts of the file specified by the current view. :ref:`MPI_File_iread` stores the number of data-type elements actually read in status. All other fields of status are undefined. It is erroneous to call this function if MPI_MODE_SEQUENTIAL mode was specified when the file was opened.

ERRORS