PropVariantGetStringElem function (propvarutil.h)

Article
02/22/2024

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

Share via