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.
Syntax
HRESULT GetNamedValue(
[in] LPCWSTR pszName,
[out] PROPVARIANT *pv
);
Parameters
[in] pszName
A pointer to a null-terminated string that contains the name of the property.
[out] pv
A pointer to a variable that receives the value for the property.
Return value
GetNamedValue returns S_OK if the operation succeeds. Otherwise, this method returns one of the error codes that are defined in Winerror.h.
Remarks
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_LPWSTR | |
| VT_LPSTR | |
| 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_UI1 | |
| VT_I2 | |
| VT_UI2 | |
| VT_I4 | |
| VT_UI4 | |
| VT_UINT | |
| 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.
Requirements
| Requirement | Value |
|---|---|
| End of support | Unavailable in UMDF 2.0 and later. |
| Target Platform | Desktop |
| Minimum UMDF version | 1.5 |
| Header | wudfddi.h (include Wudfddi.h) |
| DLL | WUDFx.dll |