MPIFilereadat(3OpenMPI) MPIFilereadat(3OpenMPI)

NAME
       MMPPIIFFiilleerreeaaddaatt  -  Reads  a  file  at  an explicitly specified offset
       (blocking, noncollective).


SSYYNNTTAAXX
       C Syntax
           #include 
           int MPIFilereadat(MPIFile fh, MPIOffset offset,
            void *buf, int count, MPIDatatype datatype,
            MPIStatus *status)

       Fortran Syntax (see FORTRAN 77 NOTES)
           INCLUDE 'mpif.h'
           MPIFILEREADAT(FH, OFFSET, BUF, COUNT,
                   DATATYPE, STATUS, IERROR)
                BUF(*)
             INTEGER FH, COUNT, DATATYPE, STATUS(MPISTATUSSIZE), IERROR
             INTEGER(KIND=MPIOFFSETKIND) OFFSET


CC++++ SSyynnttaaxx
       #include 
       void MPI::File::Readat(MPI::Offset offset, void* buf,
            int count, const MPI::Datatype& datatype,
            MPI::Status& status)

       void MPI::File::Readat(MPI::Offset offset, void* buf,
            int count, const MPI::Datatype& datatype)


IINNPPUUTT PPAARRAAMMEETTEERRSS
       fh        File handle (handle).

       offset    File offset (integer).

       count     Number of elements in buffer (integer).

       datatype  Data type of each buffer element (handle).


OOUUTTPPUUTT PPAARRAAMMEETTEERRSS
       buf       Initial address of buffer (choice).

       status    Status object (status).

       IERROR    Fortran only: Error status (integer).


DESCRIPTION
       MPIFilereadat attempts to read from the file associated with fh  (at
       the offset position) a total number of count data items having datatype
       type into 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 taken out of those parts of the file  specified  by
       the  current  view. MPIFilereadat stores the number of datatype ele-
       ments actually read in status.  All other fields of  status  are  unde-
       fined.  It  is  erroneous  to call this function if MPIMODESEQUENTIAL
       mode was specified when the file was opened.


FFOORRTTRRAANN 7777 NNOOTTEESS
       The MPI standard prescribes portable  Fortran  syntax  for  the  OFFSET
       argument only for Fortran 90. FORTRAN 77 users may use the non-portable
       syntax

            INTEGER*MPIOFFSETKIND OFFSET

       where MPIOFFSETKIND is a constant defined in  mpif.h  and  gives  the
       length of the declared integer in bytes.


EERRRROORRSS
       Almost  all MPI routines return an error value; C routines as the value
       of the function and Fortran routines in the last  argument.  C++  func-
       tions  do  not  return  errors.  If the default error handler is set to
       MPI::ERRORSTHROWEXCEPTIONS, 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   MPIERRORSRETURN.   The   error   handler  may  be  changed  with
       MPIFileseterrhandler;     the     predefined      error      handler
       MPIERRORSAREFATAL  may  be  used to make I/O errors fatal. Note that
       MPI does not guarantee that an MPI program can continue past an  error.




Open MPI 1.2                    September 2006      MPIFilereadat(3OpenMPI)