A Simple SafeArray Wrapper


The CSafeArray class is a wrapper for the SAFEARRAY datatype.
The encapsulated member can be initialized using the Init
function or using the constructor which takes the number of
dimensions and the array of bounds information.

HRESULT Init(long lnoDims, VARENUM vt,
long* lBounds)

The first parameter is the number of dimensions of the array
which is to be created. The second parameter is the array element
type. It can be any of the variant types like VT_BSTR, VT_VARIANT
etc. The third parameter is used to pass in the SAFEARRAYBOUND
information for all the dimension. For eg. if a 2 dimensional
array with 2 rows and 3 cols has to be created, the lBounds array
should be of size 4.

long lBounds[4] = {0, 3, 0, 2} //
LBound and cElements info for each dimension.

Notice that the column information is given first. Crazy
safearrays take the dimensions in the reverse order. The least
significant dimension has to be given last.

Once the array is created using either the constructor or the
Init funtion, the array elements can be retrieved or set using
the following functions

HRESULT GetElement(long* lIndex,
VARIANT* pvtElement)

HRESULT SetElement(long* lIndex, VARIANT

Again when specifying the lIndex array, the least significant
dimension should be given last.

eg For accessing the element in the 2nd row and 3rd column of
a 2 dimensional array, lIndex should be {2, 1}.

The number of elements, the lowerbound or upper bound in any
dimension can be retreived using the following functions.

long GetElementCount(long lDim)

long GetLowerBound(long lDim) and

long GetUpperBound(long lDim).

The function ReDimArray calls ::SafeArrayReDim internally.
Note that only the least significant dimension can be
redimensioned. The parameters are respectively the lBound and
cElements for the least significant dimension.

HRESULT ReDimArray(long lLBound, long

The chunk of memory allocated for the array can be accessed
using the member funtion

HRESULT AccessData(void HUGEP ** ppData),
make sure to call the counter function after use to prevent
unnecessary memory locking

HRESULT UnAccessData().

The encapsulated array member can be reteived using the
function GetSafeArray



Hope this class saves a little time with safearrays.

Concern : Tested only with 2 dimensional arrays.. But should
work for arrays of any dimension.

Download source – 2 KB

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