Emulates the SWITCH function introduced in Excel 2016.

SwitchFunction.bas

' Author: Daniel Shaw (dashaw92) - April 1, 2018
' This function emulates the behavior of SWITCH,
' a convenience function introduced in Excel 2016.
'
' To add this function to Excel, follow the steps listed on:
' https://support.office.com/en-us/article/create-custom-functions-in-excel-2f06c10b-3622-40d6-a1b2-b6748ae8231f
'
' Note: The 2016 version has a limit of 126
' conditions and results, whereas this version is
' only limited by memory. Otherwise, this should be
' cross compatible with the 2016 version.

Function SWITCH(predicate, val1, res1, ParamArray tests())
    ' Since val1 and res1 aren't optional, we can test these directly.
    If predicate = val1 Then
        SWITCH = res1
        Exit Function
    ElseIf UBound(tests) < 0 Then
        ' The predicate isn't the same as val1, and we have no other arguments.
        ' Return False.
        SWITCH = CVErr(xlErrNA)
        Exit Function
    End If
    
    For i = 0 To UBound(tests)
        ' Param array must be the last parameter in the signature,
        ' so here is a hack to implement the default parameter.
        ' If the tests array has an odd amount of arguments, we
        ' assume that the last element in the array is the default
        ' parameter. Conditions and results come in pairs.
        If i Mod 2 = 0 And i = UBound(tests) Then
            SWITCH = tests(i)
            Exit Function
        End If
        
        ' Otherwise, we'll test the value at tests[i] and return
        ' tests[i + 1] if it's true.
        If predicate = tests(i) Then
            SWITCH = tests(i + 1)
            Exit Function
        End If
    Next i
    
    ' None of the conditions passed, so return False.
    SWITCH = CVErr(xlErrNA)
End Function

It appears that when viewing workbooks created in Excel 2016 or later, SWITCH is replaced with _xlfn.SWITCH. To solve this, search and replace for _xlfn.SWITCH with SWITCH.