Describing UDT in the IDL File

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The designer of the server describes the data types of the UDT in an IDL file. The IDL file must be compiled using MIDL to generate a type library with UUID set to the UDT. Otherwise MIDL will create an alias and set UUID on that alias. This will generate a header file with the description of the UDT.

The following is an example of a type defined for a UDT:

library udttest
{
   typedef [uuid(C1D3A8C0-A4AA-11D0-819C-00A0C90FFFC3)] struct_tagUDT {
      unsigned long a1;
      BSTR pbstr;
   } UDT;

The structure, named "UDT", is defined with two data types, an unsigned long and a BSTR.

After you have generated your header file, you must fetch the IRecordInfo interface if you intend to pass a safearray of UDTs . For more information on passing a safearray of UDTs, see Fetching the IRecordInfo Interface or Passing Safearray of UDTs.

If you intend to pass a single UDT, see Passing a Single UDT.