PropVariantGetDoubleElem function (propvarutil.h)

Extracts a single double element from a PROPVARIANT structure of type VT_R8, VT_VECTOR | VT_R8, or VT_ARRAY | VT_R8.

Syntax

PSSTDAPI PropVariantGetDoubleElem(
  [in]  REFPROPVARIANT propvar,
  [in]  ULONG          iElem,
  [out] DOUBLE         *pnVal
);

Parameters

[in] propvar

Type: REFPROPVARIANT

Reference to the source PROPVARIANT structure.

[in] iElem

Type: ULONG

Specifies vector or array index; otherwise, iElem must be 0.

[out] pnVal

Type: DOUBLE*

When this function returns, contains the extracted double value.

Return value

Type: HRESULT

If this function succeeds, it returns S_OK. Otherwise, it returns an HRESULT error code.

Remarks

If the source PROPVARIANT has type VT_R8, iElem must be 0. Otherwise iElem must be less than the number of elements in the vector or array. You can use PropVariantGetElementCount to obtain the number of elements in the vector or array.

The following example uses this function to loop through the values in a PROPVARIANT structure.

Examples

// PROPVARIANT propvar;
// assume propvar is initialized and valid

if ((propvar.vt & VT_TYPEMASK) == VT_R8)
{
    UINT cElem = PropVariantGetElementCount(propvar);
    HRESULT hr = <mark type="const">S_OK</mark>;
    
    for (UINT iElem = 0; SUCCEEDED(hr) && iElem < cElem; iElem ++)
    {
        DOUBLE nValue;
        hr = PropVariantGetDoubleElem(propvar, iElem, &nValue);
    
        if (SUCCEEDED(hr))
        {
            // nValue is valid now
        }
    }
}

Requirements

See also

PropVariantGetElem