VariantToDoubleArray function (propvarutil.h)

Article
10/13/2021

Extracts an array of DOUBLE values from a VARIANT structure.

Syntax

PSSTDAPI VariantToDoubleArray(
  [in]  REFVARIANT var,
  [out] DOUBLE     *prgn,
  [in]  ULONG      crgn,
  [out] ULONG      *pcElem
);

Parameters

[in] var

Type: REFVARIANT

Reference to a source VARIANT structure.

[out] prgn

Type: DOUBLE*

Pointer to a buffer that contains crgn DOUBLE values. When this function returns, the buffer has been initialized with *pcElem DOUBLE elements extracted from the source VARIANT structure.

[in] crgn

Type: ULONG

The number of elements in the buffer pointed to by prgn.

[out] pcElem

Type: ULONG*

When this function returns, contains the count of DOUBLE elements extracted from the source VARIANT structure.

Return value

Type: HRESULT

Returns S_OK if successful, or an error value otherwise, including the following:

Return code	Description
TYPE_E_BUFFERTOOSMALL	The source VARIANT contained more than crgn values.
E_INVALIDARG	The VARIANT was not of the appropriate type.

Remarks

This helper function is used when the calling application expects a VARIANT to hold an array that consists of a fixed number of DOUBLE values.

If the source VARIANT has type VT_ARRAY | VT_DOUBLE, this function extracts up to crgn DOUBLE values and places them into the buffer pointed to by prgn.

If the VARIANT 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 VariantToDoubleArray to access a DOUBLE array stored in a VARIANT.

// VARIANT var;
// Assume variable var is initialized and valid.
DOUBLE rgDoubles[4]; // The application expects var to hold 4 DOUBLEs in an array.
ULONG cDoubles;

HRESULT hr = VariantToDoubleArray(var, rgDoubles, ARRAYSIZE(rgDoubles), &cFlags);

if (SUCCEEDED(hr))
{
    if (cFlags == ARRAYSIZE(rgDoubles))
    {
        // The application got 4 DOUBLEs which are now stored in rgDoubles.
    }
    else
    {
        // The application got *pcElem DOUBLEs which are stored in the first 
        // *pcElem elements of rgDoubles.
    }
}

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