IMFAttributes::GetAllocatedString method

Gets a wide-character string associated with a key. This method allocates the memory for the string.


HRESULT GetAllocatedString(
  REFGUID guidKey,
  LPWSTR  *ppwszValue,
  UINT32  *pcchLength



A GUID that identifies which value to retrieve. The attribute type must be MF_ATTRIBUTE_STRING.


If the key is found and the value is a string type, this parameter receives a copy of the string. The caller must free the memory for the string by calling CoTaskMemFree.


Receives the number of characters in the string, excluding the terminating NULL character. This parameter must not be NULL.

Return Value

The method returns an HRESULT. Possible values include, but are not limited to, those in the following table.

Return code Description
The method succeeded.
The specified key was not found.
The attribute value is not a string.


To copy a string value into a caller-allocated buffer, use the IMFAttributes::GetString method.

This interface is available on the following platforms if the Windows Media Format 11 SDK redistributable components are installed:

  • Windows XP with Service Pack 2 (SP2) and later.
  • Windows XP Media Center Edition 2005 with KB900325 (Windows XP Media Center Edition 2005) and KB925766 (October 2006 Update Rollup for Windows XP Media Center Edition) installed.
Note  An earlier version of the documentation incorrectly stated that the pcchLength parameter can be NULL. Setting this parameter to NULL might succeed in some cases, but is not guaranteed. The caller must pass a non-NULL pointer for this parameter.


Minimum supported client Windows Vista [desktop apps | UWP apps]
Minimum supported server Windows Server 2008 [desktop apps | UWP apps]
Target Platform Windows
Header mfobjects.h (include Mfidl.h)
Library Mfuuid.lib

See Also

Attributes and Properties