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NF:propvarutil.PropVariantToUInt32 |
PropVariantToUInt32 function (propvarutil.h) |
Extracts an ULONG value from a PROPVARIANT structure. If no value can be extracted, then a default value is assigned. |
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properties\PropVariantToUInt32.htm |
properties |
ce1d8d07-2532-48bd-be8b-7650230dbe0d |
12/05/2018 |
PropVariantToUInt32, PropVariantToUInt32 function [Windows Properties], properties.PropVariantToUInt32, propvarutil/PropVariantToUInt32, shell.PropVariantToUInt32, shell_PropVariantToUInt32 |
propvarutil.h |
Windows |
Windows XP with SP2, Windows Vista [desktop apps only] |
Windows Server 2003 with SP1 [desktop apps only] |
Propsys.lib |
Propsys.dll (version 6.0 or later) |
Windows |
Windows Desktop Search (WDS) 3.0 |
19H1 |
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Extracts an ULONG value from a PROPVARIANT structure. If no value can be extracted, then a default value is assigned.
Type: REFPROPVARIANT
A reference to a source PROPVARIANT structure.
Type: ULONG*
When this function returns, contains the extracted property value if one exists; otherwise, 0.
Type: HRESULT
If this function succeeds, it returns S_OK. Otherwise, it returns an HRESULT error code.
This helper function is used in places where the calling application expects a PROPVARIANT to hold a ULONG value. For instance, an application obtaining values from a property store can use this to safely extract the ULONG value for UInt32 properties.
If the source PROPVARIANT has type VT_UI4, this helper function extracts the ULONG value. Otherwise, it attempts to convert the value in the PROPVARIANT structure into a ULONG. If a conversion is not possible, PropVariantToUInt32 will return a failure code and set pulRet to 0. See PropVariantChangeType for a list of possible conversions. Of note, VT_EMPTY is successfully converted to 0.
The following example, to be included as part of a larger program, demonstrates how to use PropVariantToUInt32 to access a ULONG value in a PROPVARIANT.
// IPropertyStore *ppropstore;
// Assume variable ppropstore is initialized and valid
PROPVARIANT propvar = {0};
HRESULT hr = ppropstore->GetValue(PKEY_Rating, &propvar);
if (SUCCEEDED(hr))
{
// PKEY_Rating is expected to produce a VT_UI4 or VT_EMPTY value.
// PropVariantToUInt32 will convert VT_EMPTY to 0.
ULONG uRating;
hr = PropVariantToUInt32(propvar, &uRating);
if (SUCCEEDED(hr))
{
// uRating is now valid
}
else
{
// uRating is always 0
}
PropVariantClear(&propvar);
}