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PropVariantGetStringElem function (propvarutil.h)

  • Article

Extracts a single Unicode string element from a PROPVARIANT structure of type VT_LPWSTR, VT_BSTR, VT_VECTOR | VT_LPWSTR, VT_VECTOR | VT_BSTR, or VT_ARRAY | VT_BSTR.

Syntax

PSSTDAPI PropVariantGetStringElem(
  [in]  REFPROPVARIANT propvar,
  [in]  ULONG          iElem,
  [out] PWSTR          *ppszVal
);

Parameters

[in] propvar

Type: REFPROPVARIANT

Reference to a source PROPVARIANT structure.

[in] iElem

Type: ULONG

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

[out] ppszVal

Type: PWSTR*

When this function returns, contains the extracted string value. The calling application is responsible for freeing this string by calling CoTaskMemFree when it is no longer needed.

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_VECTOR | VT_LPWSTR
  • VT_VECTOR | VT_BSTR
  • VT_ARRAY | VT_BSTR
If the source PROPVARIANT has type VT_LPWSTR or VT_BSTR, 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.

If a BSTR element has a NULL pointer, this function allocates an empty string.

Examples

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

// PROPVARIANT propvar;
// Assume the variable propvar is initialized and valid

if ((propvar.vt & VT_TYPEMASK) == VT_LPWSTR || (propvar.vt & VT_TYPEMASK) == VT_BSTR)
{
    UINT cElem = PropVariantGetElementCount(propvar);
    HRESULT hr = <mark type="const">S_OK</mark>;

    for (UINT iElem = 0; SUCCEEDED(hr) && iElem < cElem; iElem ++)
    {
        PWSTR pszValue;
        hr = PropVariantGetStringElem(propvar, iElem, &pszValue);

        if (SUCCEEDED(hr))
        {
            // pszValue is valid now
            CoTaskMemFree(pszValue);
        }
    }
}

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

See also

PropVariantGetElem