PropVariantToInt64 function (propvarutil.h)

Extracts a LONGLONG value from a PROPVARIANT structure. If no value can be extracted, then a default value is assigned.

Syntax

PSSTDAPI PropVariantToInt64(
  [in]  REFPROPVARIANT propvarIn,
  [out] LONGLONG       *pllRet
);

Parameters

[in] propvarIn

Type: REFPROPVARIANT

Reference to a source PROPVARIANT structure.

[out] pllRet

Type: LONGLONG*

When this function returns, contains the extracted property value if one exists; otherwise, 0.

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 in places where the calling application expects a PROPVARIANT to hold an LONGLONG value. For instance, an application obtaining values from a property store can use this to safely extract the LONGLONG value for Int64 properties.

If the source PROPVARIANT has type VT_I8, this helper function extracts the LONGLONG value. Otherwise, it attempts to convert the value in the PROPVARIANT structure into a LONGLONG. If a conversion is not possible, PropVariantToInt64 will return a failure code and set pllRet to 0. See PropVariantChangeType for a list of possible conversions. Of note, VT_EMPTY is successfully converted to 0.

Examples

// PROPVARIANT propvar;
// Assume the variable propvar is initialized and valid
LONGLONG llValue; // The application is expecting propvar to hold a VT_I8 value
HRESULT hr = PropVariantToInt64(propvar, &llValue);
if (SUCCEEDED(hr))
{
     // llValue is valid
}                    
else
{
         // the extraction failed
}

Requirements

See also

InitPropVariantFromInt64

PropVariantChangeType

PropVariantToInt64Vector

VariantToInt64