NAME

       MPI_Type_get_contents  -  Returns  information  about arguments used in creation of a data
       type.

SYNTAX

C Syntax

       #include <mpi.h>
       int MPI_Type_get_contents(MPI_Datatype datatype, int max_integers,
            int max_addresses, int max_datatypes, int array_of_integers[], MPI_Aint array_of_addresses[], MPI_Datatype array_of_datatypes[])

Fortran Syntax (see FORTRAN 77 NOTES)

       INCLUDE 'mpif.h'
       MPI_TYPE_GET_CONTENTS(DATATYPE, MAX_INTEGERS, MAX_ADDRESSES,
                 MAX_DATATYPES, ARRAY_OF_INTEGERS, ARRAY_OF_ADDRESSES,
                 ARRAY_OF_DATATYPES, IERROR)
            INTEGER   DATATYPE, MAX_INTEGERS, MAX_ADDRESSES, MAX_DATATYPES
            INTEGER   ARRAY_OF_INTEGERS(*), ARRAY_OF_DATATYPES(*), IERROR
            INTEGER(KIND=MPI_ADDRESS_KIND) ARRAY_OF_ADDRESSES(*)

C++ Syntax

       #include <mpi.h>
       void MPI::Datatype::Get_contents(int max_integers, int max_addresses,
            int max_datatypes, int array_of_integers[],
            MPI::Aint array_of_addresses[],
            MPI::Datatype array_of_datatypes[]) const

INPUT PARAMETERS

       datatype  Data type to access (handle).

       max_integers
                 Number of elements in array_of_integers (nonnegative integer).

       max_addresses
                 Number of elements in array_of_addresses (nonnegative integer).

       max_datatypes
                 Number of elements in array_of_datatypes (nonnegative integer).

OUTPUT PARAMETERS

       array_of_integers
                 Contains integer arguments used in constructing datatype (array of integers).

       array_of_addresses
                 Contains address arguments used in constructing datatype (array of integers).

       array_of_datatypes
                 Contains data-type arguments used in constructing datatype (array of integers).

       IERROR    Fortran only: Error status (integer).

DESCRIPTION

       For the given data type, MPI_Type_get_envelope returns information on the number and  type
       of  input  arguments  used in the call that created the data type. The number-of-arguments
       values returned can be used to provide sufficiently large arrays in the  decoding  routine
       MPI_Type_get_contents.  This  call  and  the  meaning  of the returned values is described
       below. The combiner reflects the MPI data type constructor call that was used in  creating
       datatype.

       The  parameter  datatype  must be a predefined unnamed or a derived data type. The call is
       erroneous if datatype is a predefined named data type.

       The values given for max_integers, max_addresses, and max_datatypes must be  at  least  as
       large   as   the   value  returned  in  num_integers,  num_addresses,  and  num_datatypes,
       respectively, in the call MPI_Type_get_envelope for the same datatype argument.

       The data types returned in array_of_datatypes are handles to data-type  objects  that  are
       equivalent to the data types used in the original construction call. If these were derived
       data types, then the returned data types are  new  data-type  objects,  and  the  user  is
       responsible  for freeing these datatypes with MPI_Type_free. If these were predefined data
       types, then the returned data type is equal to that (constant) predefined  data  type  and
       cannot be freed.

       The  committed  state of returned derived data types is undefined, that is, the data types
       may or may not be committed. Furthermore, the content of attributes of returned data types
       is undefined.

       Note  that  MPI_Type_get_contents  can  be  invoked  with  a  data-type  argument that was
       constructed    using     MPI_Type_create_f90_real,     MPI_Type_create_f90_integer,     or
       MPI_Type_create_f90_complex  (an  unnamed  predefined data type). In such a case, an empty
       array_of_datatypes is returned.

       In the MPI-1 data-type constructor calls, the address arguments in  Fortran  are  of  type
       INTEGER.  In  the  new  MPI-2  calls,  the  address arguments are of type INTEGER(KIND=MPI
       ADDRESS KIND). The call MPI_Type_get_contents returns all addresses in an argument of type
       INTEGER(KIND=MPI  ADDRESS KIND). This is true even if the old MPI-1 calls were used. Thus,
       the location of values returned can be thought of as being returned by the C bindings.  It
       can also be determined by examining the new MPI-2 calls for data-type constructors for the
       deprecated MPI-1 calls that involve addresses.

FORTRAN 77 NOTES

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

            INTEGER*MPI_ADDRESS_KIND ARRAY_OF_ADDRESSES(*)

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

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. By default,
       this error handler aborts the MPI job, except for I/O function errors. The  error  handler
       may    be   changed   with   MPI_Comm_set_errhandler;   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.

SEE ALSO

       MPI_Type_get_envelope