NAME

       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

C++ Syntax

       #include <mpi.h>
       MPI::Request MPI::File::Iread(void* buf, int count,
            const MPI::Datatype& datatype)

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

       MPI_File_iread is a nonblocking version of 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. 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

       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. For MPI I/O
       function errors, the default error handler is set to MPI_ERRORS_RETURN. The error  handler
       may    be   changed   with   MPI_File_set_errhandler;   the   predefined   error   handler
       MPI_ERRORS_ARE_FATAL may be used to  make  I/O  errors  fatal.  Note  that  MPI  does  not
       guarantee that an MPI program can continue past an error.