VariantToBoolean function (propvarutil.h)
Extracts the value of a Boolean property from a VARIANT structure. If no value can be extracted, then a default value is assigned.
Syntax
PSSTDAPI VariantToBoolean(
[in] REFVARIANT varIn,
[out] BOOL *pfRet
);
Parameters
[in] varIn
Type: REFVARIANT
Reference to a source VARIANT structure.
[out] pfRet
Type: BOOL*
When this function returns, contains the extracted value if one exists; otherwise, FALSE.
Return value
Type: HRESULT
If this function succeeds, it returns S_OK. Otherwise, it returns an HRESULT error code.
Remarks
This helper function is used when the calling application expects a VARIANT to hold a Boolean value. For instance, an application that obtains values from a Shell folder can use this function to safely extract the value from one of the folder's Boolean properties.
If the source VARIANT is of type VT_BOOL, this function extracts the BOOL value.
If the source VARIANT is not of type VT_BOOL, this function attempts to convert the value in the VARIANT structure into a BOOL. If a conversion is not possible, VariantToBoolean returns a failure code and sets pfRet to FALSE. See PropVariantChangeType for a list of possible conversions. Of note, VT_EMPTY is successfully converted to FALSE.
Examples
The following example, to be included as part of a larger program, demonstrates how to use VariantToBoolean to access a BOOL value in a VARIANT.
// VARIANT var;
// Assume variable var is initialize and valid.
// The application expects it to hold a VT_BOOL value.
BOOL fValue;
HRESULT hr = VariantToBoolean(var, &fValue);
if (SUCCEEDED(hr))
{
// fValue is now valid.
}
else
{
// fValue is always FALSE.
}
Requirements
| Requirement | Value |
|---|---|
| Minimum supported client | Windows XP with SP2, Windows Vista [desktop apps only] |
| Minimum supported server | Windows Server 2003 with SP1 [desktop apps only] |
| Target Platform | Windows |
| Header | propvarutil.h |
| Library | Propsys.lib |
| DLL | Propsys.dll (version 6.0 or later) |
| Redistributable | Windows Desktop Search (WDS) 3.0 |