[VB6] Problem Using CopyMemory API to Get Collection Keys

[Bonnie West]

You'll want to zero out the tColElem when the loop ends. Can do this with an array of LenB(tColElem) or FillMemory API.

Here are a couple of alternative methods:

CopyMemory ByVal VarPtr(tColElem), ByVal String$(LenB(tColElem), 0), LenB(tColElem)


Private Declare Sub ZeroMemory Lib "kernel32.dll" Alias "RtlZeroMemory" (ByRef Destination As Any, ByVal Length As Long)

ZeroMemory ByVal VarPtr(tColElem), LenB(tColElem)

BTW, the Key member of the CollectionElement UDT is actually a BSTR (there's a length field and null terminator just before & after the pointed to string data), so the following lines are completely unnecessary:

Declare Function lstrlenW Lib "kernel32" (ByVal lpString As Any) As Long

Dim sKey As String

sKey = String$(lstrlenW(tColElem.Key), 0)
CopyMemory ByVal StrPtr(sKey), ByVal tColElem.Key, lstrlenW(tColElem.Key) * 2

The assignment to the string array can therefore be simplified to:

CopyMemory ByVal VarPtr(tColElem), ByVal tColElem.PtrNext, LenB(tColElem)
asKeys(lIdx) = tColElem.Key

after changing the CollectionElement.Key's data type from Long to String.