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Asked: 2026-05-11T03:41:06+00:00

Passing an undimensioned array to the VB6’s Ubound function will cause an error, so

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Passing an undimensioned array to the VB6’s Ubound function will cause an error, so I want to check if it has been dimensioned yet before attempting to check its upper bound. How do I do this?

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  1. Here’s what I went with. This is similar to GSerg’s answer, but uses the better documented CopyMemory API function and is entirely self-contained (you can just pass the array rather than ArrPtr(array) to this function). It does use the VarPtr function, which Microsoft warns against, but this is an XP-only app, and it works, so I’m not concerned.

    Yes, I know this function will accept anything you throw at it, but I’ll leave the error checking as an exercise for the reader.

    Private Declare Sub CopyMemory Lib 'kernel32' Alias 'RtlMoveMemory' _   (pDst As Any, pSrc As Any, ByVal ByteLen As Long)  Public Function ArrayIsInitialized(arr) As Boolean    Dim memVal As Long    CopyMemory memVal, ByVal VarPtr(arr) + 8, ByVal 4 'get pointer to array   CopyMemory memVal, ByVal memVal, ByVal 4  'see if it points to an address...     ArrayIsInitialized = (memVal <> 0)        '...if it does, array is intialized  End Function
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