MPIGetcount(3OpenMPI) MPIGetcount(3OpenMPI)

NAME
       MMPPIIGGeettccoouunntt  - Gets the number of top-level elements received.


SSYYNNTTAAXX
CC SSyynnttaaxx
       #include 
       int MPIGetcount(MPIStatus *status, MPIDatatype datatype,
            int *count)


FFoorrttrraann SSyynnttaaxx
       INCLUDE 'mpif.h'
       MPIGETCOUNT(STATUS, DATATYPE, COUNT, IERROR)
            INTEGER   STATUS(MPISTATUSSIZE), DATATYPE, COUNT, IERROR


CC++++ SSyynnttaaxx
       #include 
       int Status::Getcount(const Datatype& datatype) const


IINNPPUUTT PPAARRAAMMEETTEERRSS
       status    Return status of receive operation (status).

       datatype  Datatype of each receive buffer element (handle).


OOUUTTPPUUTT PPAARRAAMMEETTEERRSS
       count     Number of received elements (integer).

       IERROR    Fortran only: Error status (integer).


DESCRIPTION
       Returns the number of entries received. (We count entries, each of type
       datatype, not bytes.) The datatype argument should match  the  argument
       provided  by  the  receive  call  that  set  the  status  variable. (As
       explained in Section 3.12.5 in the  MPI-1  Standard,  "Use  of  General
       Datatypes  in Communication," MPIGetcount may, in certain situations,
       return the value MPIUNDEFINED.)

       The datatype argument is passed to  MPIGetcount  to  improve  perfor-
       mance.  A message might be received without counting the number of ele-
       ments it contains, and the count value is often not needed. Also,  this
       allows the same function to be used after a call to MPIProbe.


NNOOTTEESS
       If  the  size of the datatype is zero, this routine will return a count
       of zero.  If the amount of data in status is not an exact  multiple  of
       the  size of datatype (so that count would not be integral), a count of
       MPIUNDEFINED is returned instead.


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.  By  default, this error handler aborts the MPI job, except for
       I/O  function  errors.  The  error  handler   may   be   changed   with
       MPICommseterrhandler; the predefined error handler MPIERRORSRETURN
       may be used to cause error values to be returned. Note  that  MPI  does
       not guarantee that an MPI program can continue past an error.


SEE ALSO
       MPIGetelements





Open MPI 1.2                    September 2006         MPIGetcount(3OpenMPI)