Unpack a datatype into contiguous memory


#include "mpi.h"
int MPI_Unpack ( inbuf, insize, position, outbuf, outcount, datatype, comm )
void         *inbuf;
int           insize;
int          *position;
void         *outbuf;
int           outcount;
MPI_Datatype  datatype;
MPI_Comm      comm;

Input Parameters

inbuf input buffer start (choice)
insize size of input buffer, in bytes (integer)
position current position in bytes (integer)
outcount number of items to be unpacked (integer)
datatype datatype of each output data item (handle)
comm communicator for packed message (handle)

Output Parameter

output buffer start (choice)

Notes for Fortran

All MPI routines in Fortran (except for MPI_WTIME and MPI_WTICK) havean additional argument ierr at the end of the argument list. ierris an integer and has the same meaning as the return value of the routinein C. In Fortran, MPI routines are subroutines, and are invoked with thecall statement.

All MPI objects (e.g., MPI_Datatype, MPI_Comm) are of type INTEGERin Fortran.


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 lastargument. Before the value is returned, the current MPI error handler iscalled. By default, this error handler aborts the MPI job. The error handlermay be changed with MPI_Errhandler_set; the predefined error handlerMPI_ERRORS_RETURN may be used to cause error values to be returned. Note that MPI does not guarentee that an MPI program can continue pastan error.

No error; MPI routine completed successfully.
Invalid communicator. A common error is to use a null communicator in a call (not even allowed in MPI_Comm_rank).
Invalid count argument. Count arguments must be non-negative; a count of zero is often valid.
Invalid datatype argument. May be an uncommitted MPI_Datatype (see MPI_Type_commit).
Invalid argument. Some argument is invalid and is not identified by a specific error class (e.g., MPI_ERR_RANK).

See Also

MPI_Pack, MPI_Pack_size