MSDN > Windows API Reference > Win32 API > Functions > OLE32

OLE32 Functions

This section details the functions available in the OLE32.dll library, which provides core support for OLE (Object Linking and Embedding) and COM (Component Object Model) technologies in Windows.

Core OLE Functions

Moniker and Binding Functions

Structured Storage Functions

CoCreateInstance

Creates a single, uninitialized object of the specified type and, optionally, commits it to the running object table (ROT).

HRESULT CoCreateInstance(REFCLSID rclsid, LPUNKNOWN pUnkOuter, DWORD dwClsContext, REFIID riid, LPVOID *ppv);

Parameters

Name Type Description
rclsid REFCLSID A reference to the CLSID of the object to be created.
pUnkOuter LPUNKNOWN If NULL, this parameter indicates that the object is not being created as part of an aggregate. If non-NULL, this parameter is a pointer to the aggregatee's controlling unknown.
dwClsContext DWORD The context in which the code that creates the executable object will run.
riid REFIID A reference to the IID of the interface to be used to communicate with the newly created object.
ppv LPVOID * An indirect pointer to the interface specified in riid. Upon successful return, *ppv contains the pointer to the queried interface.

Return Value

If the function succeeds, the return value is S_OK. Otherwise, it is an error code.

CoInitialize

Initializes the COM library for the current apartment.

HRESULT CoInitialize(LPVOID pvReserved);

Parameters

Name Type Description
pvReserved LPVOID Reserved. Must be NULL.

Return Value

If the function succeeds, the return value is S_OK. If the COM library is already initialized, the function returns S_FALSE. Otherwise, it is an error code.

You must call CoInitializeEx or CoInitialize on each thread that uses COM. It is recommended to use CoInitializeEx with the appropriate concurrency model.

CoUninitialize

Closes the COM library.

void CoUninitialize(void);

Remarks

This function closes the COM library. It should be called once for every successful call to CoInitializeEx or CoInitialize.

CoGetClassObject

Provides a way to connect to a class object of the specified class.

HRESULT CoGetClassObject(REFCLSID rclsid, DWORD dwClsContext, LPCOSERVERINFO pServerInfo, REFIID riid, LPVOID *ppv);

Parameters

Name Type Description
rclsid REFCLSID A reference to the CLSID of the class object to retrieve.
dwClsContext DWORD The context in which the executable code is to be run.
pServerInfo LPCOSERVERINFO A pointer to a COSERVERINFO structure that specifies the server to connect to. Can be NULL.
riid REFIID A reference to the interface identifier of the desired interface.
ppv LPVOID * An indirect pointer to the interface identifier specified by riid.

Return Value

If the function succeeds, the return value is S_OK. Otherwise, it is an error code.

CoRegisterClassObject

Registers an application's class object with OLE so that it can be used to create instances of the class.

HRESULT CoRegisterClassObject(REFCLSID rclsid, LPUNKNOWN pUnk, DWORD dwClsContext, DWORD flags, LPDWORD pdwRegister);

Parameters

Name Type Description
rclsid REFCLSID The CLSID of the class being registered.
pUnk LPUNKNOWN A pointer to the class object's implementation of the IClassFactory interface.
dwClsContext DWORD The context in which the executable code is to be run.
flags DWORD One of the REGCLS enumeration values.
pdwRegister LPDWORD A pointer to a value that identifies the registered class. This value can be passed to CoRevokeClassObject.

Return Value

If the function succeeds, the return value is S_OK. Otherwise, it is an error code.

CoRevokeClassObject

Removes a class object's registration from the OLE component object model's central registration database.

HRESULT CoRevokeClassObject(DWORD dwRegister);

Parameters

Name Type Description
dwRegister DWORD The registration number obtained from a previous call to CoRegisterClassObject.

Return Value

If the function succeeds, the return value is S_OK. Otherwise, it is an error code.

StringFromGUID2

Converts a GUID into a string representation.

int StringFromGUID2(REFGUID rguid, LPOLESTR lpsz, int cchMax);

Parameters

Name Type Description
rguid REFGUID The GUID to convert.
lpsz LPOLESTR A pointer to the buffer that receives the string representation of the GUID.
cchMax int The size of the buffer pointed to by lpsz, in characters.

Return Value

If the function succeeds, the return value is the number of characters in the string, including the null terminator. If the buffer is too small, the return value is 0, and the contents of the buffer are undefined. Otherwise, it is an error code.

CLSIDFromString

Converts a string representation of a CLSID into a CLSID structure.

HRESULT CLSIDFromString(LPOLESTR lpsz, LPCLSID pclsid);

Parameters

Name Type Description
lpsz LPOLESTR A pointer to the string representation of the CLSID.
pclsid LPCLSID A pointer to the CLSID structure that will receive the converted CLSID.

Return Value

If the function succeeds, the return value is S_OK. Otherwise, it is an error code.