MPI_File_read(3)                   Open MPI                   MPI_File_read(3)



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
           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.




1.4.1                            Jan 14, 2010                 MPI_File_read(3)
