LoadTypeLib function (oleauto.h)

Article
02/22/2024

Loads and registers a type library.

Syntax

HRESULT LoadTypeLib(
  LPCOLESTR szFile,
  ITypeLib  **pptlib
);

Parameters

szFile

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

pptlib

The loaded type library.

Return value

This function can return one of these values.

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

Remarks

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.

Requirements

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

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