switch or case statement for excel spreadsheet 1

Function sw(ParamArray invar())
    ' implement logic similar to switch
    ' example call
    '  =switch(boolean1, value1, boolean2, value2, boolean3, value3....)
    '    returns the value corresponding to the first true boolean

    ' at least one of the boolean expressions must be true
    ' requires an even number of arguments
    ' the syntax is pretty much identical to vba switch, except that there is no explicit allowance for else value
    ' if you want an else clause, enter true for the next to last argument, followed by the associated value

    ' Note that indexing of invar starts at 0, regardless of Option Base statement

    ' Check to confirm even number of arguments (as required)
    If UBound(invar) Mod 2 <> 1 Then MsgBox "Error: Need even number of arguments for sw"
    Dim ctr As Long        ' loop counter
    Dim tempswitch As Variant        ' variable which will hold the output value

    ctr = 0        ' initialize counter
    Do While True        ' loop until broken by exit command
        ' Check for boolean input
        If VarType(invar(ctr)) <> vbBoolean Then MsgBox "Error 1st 3rd 5th etc arguments of sw must be boolean"
        If invar(ctr) Then        ' in this case have found a true value, assign function and exit
            tempswitch = invar(ctr + 1)
            sw = tempswitch
            Exit Do
        Else        ' Else have not found true yet, update counter and continue loop
            ctr = ctr + 2
        End If

        ' Check for reaching end of invar without having found true
        If ctr + 1 > UBound(invar) Then MsgBox "Error: sw needs at least one true boolean argument"

    Loop

End Function