NAME

       MPI_File_read  -  Reads  a  file starting at the location specified by the individual file
       pointer (blocking, noncollective).

SYNTAX

C Syntax

       #include <mpi.h> int MPI_File_read(MPI_File fh, void *buf,       int  count,  MPI_Datatype
       datatype, MPI_Status *status)

Fortran Syntax

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

C++ Syntax

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

       void MPI::File::Read(void* buf, int count,
            const MPI::Datatype& datatype)

INPUT PARAMETERS

       fh        File handle (handle).

       count     Number of elements in buffer (integer).

       datatype  Data type of each buffer element (handle).

OUTPUT PARAMETERS

       buf       Initial address of buffer (integer).

       status    Status object (status).

       IERROR    Fortran only: Error status (integer).

DESCRIPTION

       MPI_File_read attempts to read from the file associated with fh (at the current individual
       file pointer position maintained by the system) a total number of count data items  having
       datatype  type  into  the  user's buffer buf.  The data is taken out of those parts of the
       file specified by the current view. MPI_File_read 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.