MPI_Get_count
Gets the number of "top level" elements
Synopsis
int MPI_Get_count(const MPI_Status * status, MPI_Datatype datatype, int *count)
Input Parameters
- status
- return status of receive operation (Status)
- datatype
- datatype of each receive buffer element (handle)
Output Parameters
- count
- number of received elements (integer)
Notes:
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
MPI_UNDEFINED is returned instead.
Notes for Fortran
All MPI routines in Fortran (except for MPI_WTIME and MPI_WTICK) have
an additional argument ierr at the end of the argument list. ierr
is an integer and has the same meaning as the return value of the routine
in C. In Fortran, MPI routines are subroutines, and are invoked with the
call statement.
All MPI objects (e.g., MPI_Datatype, MPI_Comm) are of type INTEGER
in Fortran.
Errors
All MPI routines (except MPI_Wtime and MPI_Wtick) return an error value;
C routines as the value of the function and Fortran routines in the last
argument. Before the value is returned, the current MPI error handler is
called. By default, this error handler aborts the MPI job. The error handler
may be changed with MPI_Comm_set_errhandler (for communicators),
MPI_File_set_errhandler (for files), and MPI_Win_set_errhandler (for
RMA windows). The MPI-1 routine MPI_Errhandler_set may be used but
its use is deprecated. The predefined error handler
MPI_ERRORS_RETURN 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; however, MPI implementations will attempt to continue whenever
possible.
- MPI_SUCCESS
- No error; MPI routine completed successfully.
- MPI_ERR_TYPE
- Invalid datatype argument. Additionally, this error can
occur if an uncommitted MPI_Datatype (see MPI_Type_commit) is used
in a communication call.