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IWDFNamedPropertyStore::GetNamedValue method (wudfddi.h)

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[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

See also

IWDFNamedPropertyStore

PROPVARIANT

PropVariantClear