StgCreatePropStg function

The StgCreatePropStg function creates and opens a property set in a specified storage or stream object. The property set supplies the system-provided, stand-alone implementation of the IPropertyStorage interface.


HRESULT StgCreatePropStg(
  IUnknown         *pUnk,
  REFFMTID         fmtid,
  const CLSID      *pclsid,
  DWORD            grfFlags,
  DWORD            dwReserved,
  IPropertyStorage **ppPropStg



A pointer to the IUnknown interface on the storage or stream object that stores the new property set.


The FMTID of the property set to be created.


A Pointer to the initial CLSID for this property set. May be NULL, in which case pclsid is set to all zeroes.


The values from PROPSETFLAG Constants that determine how the property set is created and opened.


Reserved; must be zero.


The address of an IPropertyStorage* pointer variable that receives the interface pointer to the new property set.

Return Value

This function supports the standard return values E_INVALIDARG and E_UNEXPECTED, in addition to the following:


StgCreatePropStg creates and opens a new property set which supplies the system-provided, stand-alone implementation of the IPropertyStorage interface. The new property set is contained in the storage or stream object specified by pUnk. The value of the grfFlags parameter indicates whether pUnk specifies a storage or stream object. For example, if PROPSETFLAG_NONSIMPLE is set, then pUnk can be queried for an IStorage interface on a storage object.

In either case, this function calls pUnk->AddRef for the storage or stream object containing the property set. It is the responsibility of the caller to release the object when it is no longer needed.

This function is similar to the IPropertySetStorage::Create method. However, StgCreatePropStg adds the pUnk parameter and supports the PROPSETFLAG_UNBUFFERED value for the grfFlags parameter. Use this function instead of the Create method if you have an IStorage interface that does not support the IPropertySetStorage interface, or if you want to use the PROPSETFLAG_UNBUFFERED value. For more information about using this PROPSETFLAG_UNBUFFERED enumeration value, see PROPSETFLAG Constants.

The property set automatically contains code page and locale identifier (ID) properties. These are set to the current system default and the current user default, respectively.

The grfFlags parameter is a combination of values taken from PROPSETFLAG Constants. The new enumeration value PROPSETFLAG_UNBUFFERED is supported. For more information, see PROPSETFLAG Constants.

This function is exported out of the redistributable Iprop.dll, which is included in Windows NT 4.0 with Service Pack 2 (SP2) and later and available as a redistributable in Windows 95, Windows 98 and later. In Windows 2000 and Windows XP, it is exported out of ole32.dll. It can also be exported out of iprop.dll in Windows 2000 and Windows XP, but the call gets forwarded to ole32.dll.


Minimum supported client Windows 2000 Professional [desktop apps | UWP apps]
Minimum supported server Windows 2000 Server [desktop apps | UWP apps]
Target Platform Windows
Header coml2api.h (include Propidl.h)
Library Ole32.lib
DLL Ole32.dll

See Also


IPropertySetStorage-Stand-alone Implementation


IPropertyStorage-Stand-alone Implementation