PropVariantToUInt32Vector function (propvarutil.h)

Article
10/13/2021

Extracts data from a PROPVARIANT structure into an ULONG vector.

Syntax

PSSTDAPI PropVariantToUInt32Vector(
  [in]  REFPROPVARIANT propvar,
  [out] ULONG          *prgn,
  [in]  ULONG          crgn,
  [out] ULONG          *pcElem
);

Parameters

[in] propvar

Type: REFPROPVARIANT

Reference to a source PROPVARIANT structure.

[out] prgn

Type: ULONG*

Points to a buffer containing crgn ULONG values. When this function returns, the buffer has been initialized with pcElem ULONG elements extracted from the source PROPVARIANT.

[in] crgn

Type: ULONG

Size of the buffer pointed to by prgn, in elements.

[out] pcElem

Type: ULONG*

When this function returns, contains the count of ULONG values extracted from the source PROPVARIANT structure.

Return value

Type: HRESULT

This function can return one of these values.

Return code	Description
S_OK	Returns S_OK if successful, or an error value otherwise.
TYPE_E_BUFFERTOOSMALL	The source PROPVARIANT contained more than crgn values. The buffer pointed to by prgn is too small.
E_INVALIDARG	The PROPVARIANT was not of the appropriate type.

Remarks

This helper function is used in places where the calling application expects a PROPVARIANT to hold a vector of ULONG values with a fixed number of elements.

If the source PROPVARIANT has type VT_VECTOR | VT_UI4 or VT_ARRAY | VT_UI4, this helper function extracts up to crgn ULONG values and places them into the buffer pointed to by prgn. If the PROPVARIANT contains more elements than will fit into the prgn buffer, this function returns an error and sets pcElem to 0.

Examples

The following example, to be included as part of a larger program, demonstrates how to use PropVariantToUInt32Vector to access a ULONG vector value in a PROPVARIANT.

// PROPVARIANT propvar;
// Assume the variable propvar is initialized and valid
ULONG rgLongs[4]; // The application is expecting propvar to hold 4 ULONGs in a vector
ULONG cElems;
HRESULT hr = PropVariantToUInt32Vector(propvar, rgLongs, ARRAYSIZE(rgLongs), &cElems);
if (SUCCEEDED(hr))
{
     if (cElems == ARRAYSIZE(rgLongs))
     {
         // The application got 4 ULONGs which are now stored in rgLongs
     }
     else
     {
         // The application got cElems which are stored in the first cElems elements of rgLongs
     }
}

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

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