IWDFNamedPropertyStore::GetNamedValue method (wudfddi.h)
[Warning: UMDF 2 is the latest version of UMDF and supersedes UMDF 1. All new UMDF drivers should be written using UMDF 2. No new features are being added to UMDF 1 and there is limited support for UMDF 1 on newer versions of Windows 10. Universal Windows drivers must use UMDF 2. For more info, see Getting Started with UMDF.]
The GetNamedValue method retrieves the value of a property.
HRESULT GetNamedValue( [in] LPCWSTR pszName, [out] PROPVARIANT *pv );
A pointer to a null-terminated string that contains the name of the property.
A pointer to a variable that receives the value for the property.
GetNamedValue returns S_OK if the operation succeeds. Otherwise, this method returns one of the error codes that are defined in Winerror.h.
The GetNamedValue method allocates memory for a string in the PROPVARIANT structure pointed to by the pv parameter. The caller must then free this memory by calling the PropVariantClear function, as shown in the following snippet:
hr = pPropStore->GetNamedValue(L"Host", &val); ... PropVariantClear(&val);
If the caller does not free the memory, a memory leak may result.
The following variant types are supported for property values. The following table shows the variant type that is returned regardless of the original variant type.
|Variant type||Variant type retrieved|
|VT_BSTR||While clients read a string value, the value is returned as VT_LPWSTR regardless of the original variant type that was used to write the value.|
|VT_I1||While clients read an integer value, the value is returned as VT_UI4 regardless of the original variant type that was used to write the value.|
|VT_BLOB||The binary value is returned as VT_BLOB.|
|VT_VECTOR | VT_LPWSTR||The string array is returned as VT_VECTOR | VT_LPWSTR|
A string that contains environment variables is expanded on read.
For more information, see Using the Registry in UMDF-based Drivers.
|End of support||Unavailable in UMDF 2.0 and later.|
|Minimum UMDF version||1.5|
|Header||wudfddi.h (include Wudfddi.h)|