ITypeLib interface (oaidl.h)

Represents a type library, the data that describes a set of objects. A type library can be a stand-alone binary file (.TLB), a resource in a dynamic link library or executable file (.DLL, .OLB, or .EXE).


The ITypeLib interface inherits from the IUnknown interface. ITypeLib also has these types of members:


The ITypeLib interface has these methods.


Finds occurrences of a type description in a type library. This may be used to quickly verify that a name exists in a type library.

Retrieves the documentation string for the library, the complete Help file name and path, and the context identifier for the library Help topic in the Help file.

Retrieves the structure that contains the library's attributes.

Enables a client compiler to bind to the types, variables, constants, and global functions for a library.

Retrieves the specified type description in the library.

Provides the number of type descriptions that are in a type library.

Retrieves the type description that corresponds to the specified GUID.

Retrieves the type of a type description.

Indicates whether a passed-in string contains the name of a type or member described in the library.

Releases the TLIBATTR originally obtained from GetLibAttr.


The system registry contains a list of all the installed type libraries. Type library organization is illustrated in the following figure:

Diagram showing the organization of installed type libraries as they are listed in the system registry.

The ITypeLib interface provides methods for accessing a library of type descriptions. This interface supports the following:

  • Generalized containment for type information. ITypeLib allows iteration over the type descriptions contained in the library.
  • Global functions and data. A type library can contain descriptions of a set of modules (.DLLs) that exports data and functions. The type library supports compiling references to the exported data and functions.
  • General information, including a user-readable name for the library and help for the library as a whole.


Target Platform Windows
Header oaidl.h

See also

Type Description Interfaces and Functions