excelvba large hexadecimal string to decimal code example

Example: excelvba large hexadecimal string to decimal

'VBA function to convert a hexadecimal string into a decimal. Uses
'the Decimal Variant subtype to allow for much larger values than the
'worksheet function HEX2DEC() or CLng("&h" & HexVal) can achieve. It 
'returns an UNSIGNED Decimal integer...


Function HexToDec(hexStr$)
    Dim c&, i&, bitVal
    Static hexVals&(), b() As Byte
    
    If (Not Not hexVals) = 0 Then
        ReDim hexVals(48 To 102)
        For i = 48 To 57
            hexVals(i) = c
            c = c + 1
        Next
        For i = 65 To 70
            hexVals(i) = c
            c = c + 1
        Next
        c = 10
        For i = 97 To 102
            hexVals(i) = c
            c = c + 1
        Next
    End If
    
    bitVal = CDec(1)
    HexToDec = CDec(0)
    b = StrConv(hexStr, vbFromUnicode)
    For i = UBound(b) To 0 Step -1
        HexToDec = HexToDec + hexVals(b(i)) * bitVal
        bitVal = bitVal * 16&
    Next
End Function



'-------------------------------------------------------------------------------------

MsgBox HexToDec("fffffffffffffffffffffff")	'<--displays: 4951760157141521099596496895

MsgBox TypeName(HexToDec("ABCDEF0123456"))	'<--displays: Decimal

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