LoadTypeLib function (oleauto.h)

Loads and registers a type library.


HRESULT LoadTypeLib(
  ITypeLib  **pptlib



The name of the file from which the method should attempt to load a type library.


The loaded type library.

Return value

This function can return one of these values.

Return code Description
One or more of the arguments is not valid.
Insufficient memory to complete the operation.
The function could not write to the file.
The type library could not be opened.
The function could not read from the file.
The type library has an older format.
The LCID could not be found in the OLE-supported DLLs.
The type library or DLL could not be loaded.


The function LoadTypeLib loads a type library (usually created with MkTypLib) that is stored in the specified file. If szFile specifies only a file name without any path, LoadTypeLib searches for the file and proceeds as follows:

  • If the file is a stand-alone type library implemented by Typelib.dll, the library is loaded directly.
  • If the file is a DLL or an executable file, it is loaded. By default, the type library is extracted from the first resource of type ITypeLib. To load a different type of library resource, append an integer index to szFile. For example:
    ITypeLib *ptlib;
    LoadTypeLib("C:\\MONTANA\\EXE\\MFA.EXE\\3", &ptlib)

    This statement loads the type library resource 3 from the file Mfa.exe file.

  • If the file is none of the above, the file name is parsed into a moniker (an object that represents a file-based link source), and then bound to the moniker. This approach allows LoadTypeLib to be used on foreign type libraries, including in-memory type libraries. Foreign type libraries cannot reside in a DLL or an executable file. For more information on monikers, see the COM Programmer's Reference.
If the type library is already loaded, LoadTypeLib increments the type library's reference count and returns a pointer to the type library.

For backward compatibility, LoadTypeLib will register the type library if the path is not specified in the szFile parameter. LoadTypeLib will not register the type library if the path of the type library is specified. It is recommended that RegisterTypeLib be used to register a type library.


Target Platform Windows
Header oleauto.h
Library OleAut32.lib
DLL OleAut32.dll