signed result of Val function in VBA

I use vba in ms access,and found that ,if my parameter greater than 0x8000 less than 0x10000, the result is minus number

eg. Val("&H8000") = -32768 Val("&HFFFF")= -1

how can i get the unsigned number?
thanks!

There's a problem right here:

?TypeName(&HFFFF)
Integer

The Integer type is 16-bit, and 65,535 overflows it. This is probably overkill, but it was fun to write:

Function ConvertHex(ByVal value As String) As Double
    
    If Left(value, 2) = "&H" Then
        value = Right(value, Len(value) - 2)
    End If
    
    Dim result As Double
    
    Dim i As Integer, j As Integer
    For i = Len(value) To 1 Step -1
        
        Dim digit As String
        digit = Mid$(value, i, 1)
        
        result = result + (16 ^ j) * Val("&H" & digit)
        j = j + 1
        
    Next
    
    ConvertHex = result
    
End Function

This function iterates each digit starting from the right, computing its value and adding it to the result as it moves to the leftmost digit.

?ConvertHex("&H10")
 16 
?ConvertHex("&HFF")
 255 
?ConvertHex("&HFFFF")
 65535 
?ConvertHex("&HFFFFFFFFFFFFF")
 281474976710655 

UPDATE

As I suspected, there's a much better way to do this. Credits to @Jonbot for this one:

Function ConvertHex(ByVal value As String) As Currency
    Dim result As Currency
    result = CCur(value)

    If result < 0 Then
        'Add two times Int32.MaxValue and another 2 for the overflow
        'Because the hex value is apparently parsed as a signed Int64/Int32
        result = result + &H7FFFFFFF + &H7FFFFFFF + 2
    End If

    ConvertHex = result
End Function