PropVariantToUInt16WithDefault function (propvarutil.h)

Extracts an unsigned short value from a PROPVARIANT structure. If no value exists, then the specified default value is returned.

Syntax

PSSTDAPI_(USHORT) PropVariantToUInt16WithDefault(
  [in] REFPROPVARIANT propvarIn,
  [in] USHORT         uiDefault
);

Parameters

[in] propvarIn

Type: REFPROPVARIANT

Reference to a source PROPVARIANT structure.

[in] uiDefault

Type: USHORT

Specifies a default property value, for use where no value currently exists.

Return value

Type: unsigned short

Returns extracted unsigned short value, or default.

Remarks

This helper function is used in places where the calling application expects a PROPVARIANT to hold a unsigned short value. For instance, an application obtaining values from a property store can use this to safely extract the unsigned short value for UInt16 properties.

If the source PROPVARIANT has type VT_UI2, this helper function extracts the unsigned short value. Otherwise, it attempts to convert the value in the PROPVARIANT structure into a unsigned short. If a conversion is not possible, PropVariantToUInt16 will return a failure code and set puiRet to 0. See PropVariantChangeType for a list of possible conversions. Of note, VT_EMPTY is successfully converted to 0.

Examples

The following example, to be included as part of a larger program, demonstrates how to use PropVariantToUInt16 to access a unsigned short value in a PROPVARIANT.

// IPropertyStore *ppropstore;

// Assume variable ppropstore is initialized and valid

PROPVARIANT propvar = {0};

HRESULT hr = ppropstore->GetValue(PKEY_FlagColor, &propvar);

if (SUCCEEDED(hr))

{

     // PKEY_FlagColor is expected to produce a VT_UI2 or VT_EMPTY value.

     // PropVariantToInt32 will convert VT_EMPTY to 0.

     USHORT uColor;

     hr = PropVariantToUInt32(propvar, & uColor);

     if (SUCCEEDED(hr))

     {

             // uColor is now valid

     }

     else

     {

             // uColor is always 0

     }

     PropVariantClear(&propvar);

}

Requirements

See also

InitPropVariantFromUInt16

PropVariantChangeType

PropVariantToUInt16Vector

VariantToUInt16