InitPropVariantFromPropVariantVectorElem function (propvarutil.h)

Initializes a PROPVARIANT structure based on a specified PROPVARIANT vector element.

Syntax

PSSTDAPI InitPropVariantFromPropVariantVectorElem(
  [in]  REFPROPVARIANT propvarIn,
  [in]  ULONG          iElem,
  [out] PROPVARIANT    *ppropvar
);

Parameters

[in] propvarIn

Type: REFPROPVARIANT

The source PROPVARIANT structure.

[in] iElem

Type: ULONG

The index of the source PROPVARIANT structure element.

[out] ppropvar

Type: PROPVARIANT*

When this function returns, contains the initialized PROPVARIANT structure.

Return value

Type: HRESULT

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

Remarks

This helper function works for PROPVARIANT structures of the following types:

• VT_LPWSTR
• VT_BSTR
• VT_BOOL
• VT_I2
• VT_I4
• VT_I8
• VT_U12
• VT_U14
• VT_U18
• VT_FILETIME
• VT_VECTOR | (any one of VT_LPWSTR, VT_BSTR, VT_BOOL, VT_I2, VT_I4, VT_I8, VT_U12, VT_U14, VT_U18, VT_FILETIME)
• VT_ARRAY | (any one of VT_BSTR, VT_BOOL, VT_I2, VT_I4, VT_I8, VT_U12, VT_U14, VT_U18)

This function extracts a single value from the source PROPVARIANT structure and uses that value to initialize the output PROPVARIANT structure. The calling application must use PropVariantClear to free the PROPVARIANT referred to by ppropvar when it is no longer needed.

If the source PROPVARIANT is a vector or array, iElem must be less than the number of elements in the vector or array.

If the source PROPVARIANT has a single value, iElem must be 0.

If the source PROPVARIANT is empty, this function always returns an error code.

You can use PropVariantGetElementCount to obtain the number of elements in the vector or array.

Examples

The following code example, to be included as part of a larger program, demonstrates how to use InitPropVariantFromPropVariantVectorElem in an iteration statement to access the values in a PROPVARIANT.

// PROPVARIANT propvar;
// Assume propvar is initialized and valid.
UINT cElem = PropVariantGetElementCount(propvar);
HRESULT hr = <mark type="const">S_OK</mark>;

for (UINT iElem = 0; SUCCEEDED(hr) && iElem < cElem; iElem ++)
{
    PROPVARIANT propvarElem = {0};

    hr = InitPropVariantFromPropVariantVectorElem(propvar, iElem, &propvarElem);

    if (SUCCEEDED(hr))
    {
        // propvarElem is now valid.

        PropVariantClear(&propvarElem);
    }
}

Requirements

See also

PropVariantGetElem