Is there a more concise way of using Select Case here?

Question

I'm testing an input to see if it consists of Japanese characters, which fall within a certain unicode block. I could do it with If, but I like the neater syntax for Select Case. Said that, I'm not quite sure how to write a "Case" that excludes numbers falling between two values.

This works, but could possibly be written more concisely:

For Each c As Char In jpstring
    Select Case AscW(c)
        Case 12352 To 12543, 12784 To 12799

        Case Else
            Return False
    End Select
Next

I tried doing something like:

Case Not 12352 To 12543, 12784 To 12799

But that doesn't work, and nor does wrapping it in brackets like below:

Case Not (12352 To 12543, 12784 To 12799)

Is there a way to write a Case so that it specifically excludes multiple ranges of numbers?

Answer 1

AFAIK there is no way to have a Case match an excluded range. However, you could use > and < :

For Each c As Char In jpstring
    Select Case AscW(c)
        Case < 12352, 12544 To 12783, > 12799
            Return False
        Case Else

    End Select
Next

Of course, if you only want to return True or False , it may be more concise to simply return the result of the comparison:

For Each c As Char In jpstring
    Dim asc = AscW(c)
    Return asc < 12352 OrElse (asc >= 12544 AndAlso asc <= 12783) OrElse asc > 12799
Next

Answer 2

How about some LINQ?

Dim j() as Char = inputText.Select(Function(c) Ascw(c)).Where(Function(i) (i > 12351 AndAlso i < 12544) OrElse (i > 12783 AndAlso i < 12800))

Making an extension method might also be a nice way to tidy things up:

Module CharExtensions

    <Extension()> 
    Public Sub IsJapanese(c As char)
        Dim i = AscW(c)
        Return (i > 12351 AndAlso i < 12544) OrElse (i > 12783 AndAlso i < 12800
    End Sub
End Module



   Dim j() as Char = inputText.Where(Function(c) c.IsJapanese)