CoCreateInstance

CoCreateInstance

COM

CoCreateInstance

Creates a single uninitialized object of the class associated with a specified CLSID. Call CoCreateInstance when you want to create only one object on the local system. To create a single object on a remote system, call CoCreateInstanceEx, as CoCreateInstance requires that the HKCR\APPID\{appid}\RemoteServerName key be set to specify where remote activation of the object must occur. To create multiple objects based on a single CLSID, refer to the CoGetClassObject function.

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

Parameters

rclsid: [in] CLSID associated with the data and code that will be used to create the object.

pUnkOuter: [in] If NULL, indicates that the object is not being created as part of an aggregate. If non-NULL, pointer to the aggregate object's IUnknown interface (the controlling IUnknown).

dwClsContext: [in] Context in which the code that manages the newly created object will run. The values are taken from the enumeration CLSCTX.

riid: [in] Reference to the identifier of the interface to be used to communicate with the object.

ppv: [out] Address of pointer variable that receives the interface pointer requested in riid. Upon successful return, *ppv contains the requested interface pointer. Upon failure, *ppv contains NULL.

Return Values

S_OK: An instance of the specified object class was successfully created.

REGDB_E_CLASSNOTREG: A specified class is not registered in the registration database. Also can indicate that the type of server you requested in the CLSCTX enumeration is not registered or the values for the server types in the registry are corrupt.

CLASS_E_NOAGGREGATION: This class cannot be created as part of an aggregate.

E_NOINTERFACE: The specified class does not implement the requested interface, or the controlling IUnknown does not expose the requested interface.

Remarks

The CoCreateInstance helper function provides a convenient shortcut by connecting to the class object associated with the specified CLSID, creating an uninitialized instance, and releasing the class object. As such, it encapsulates the following functionality:

CoGetClassObject(rclsid, dwClsContext, NULL, IID_IClassFactory, &pCF); 
hresult = pCF->CreateInstance(pUnkOuter, riid, ppvObj) 
pCF->Release();

It is convenient to use CoCreateInstance when you need to create only a single instance of an object on the local machine. If you are creating an instance on remote machine, call CoCreateInstanceEx. When you are creating multiple instances, it is more efficient to obtain a pointer to the class object's IClassFactory interface and use its methods as needed. In the latter case, you should use the CoGetClassObject function.

In the CLSCTX enumeration, you can specify the type of server used to manage the object. The constants can be CLSCTX_INPROC_SERVER, CLSCTX_INPROC_HANDLER, CLSCTX_LOCAL_SERVER, or any combination of these values. The constant CLSCTX_ALL is defined as the combination of all three. For more information about the use of one or a combination of these constants, refer to CLSCTX.

Requirements

For an explanation of the requirement values, see Requirements (COM).

Windows NT/2000/XP: Requires Windows NT 3.1 or later.

Windows 95/98: Requires Windows 95 or later.

Header: Declared in objbase.h.

Library: Use ole32.lib.