CODEWITHSUNDEEP
vb.netswitch-statementconditional-statementsselect-case
kurozakura
kurozakura

Reputation: 2349

Select Case Fall through with Not Condition in VB.NET

How to Add Not condition in the below select case.

Is <> works for single value, and 'To' works for a Range but the value are specific values there are not series of numbers. Is it possible to use select case in this scenario, or do i have to switch to if-else. Ex: i don't want case to execute when value is 0 and 3

           Select value
             case 0,1,2,3
           End Select

Upvotes: 4

Views: 13209

Answers (3)

Cody Gray
Cody Gray

Reputation: 244782

I'm not sure I understand the question...

Why can't you just write the example code like so:

Select Case value
    Case 1, 2
        DoWork()
End Select

Nothing gets executed when value = 0 or value = 3. The series of values provided to a Case statement doesn't have to be sequential.

Update in response to comment:

I would write that like this, taking advantage of the Case Else label:

Select Case myComboBox.SelectedIndex
    Case 1, 5, 8
        'The suggestion is acceptable, so process it
        DoWork()
    Case Else
        'The suggestion is invalid, so show an error
        MessageBox.Show("You cannot select that option. " & _
                        "Please choose options 1, 5, or 8 instead.", _
                        "Invalid Selection", _
                        MessageBoxButtons.OK, MessageBoxIcon.Error)
End Select

Of course, if you don't actually have any "work" to be done in the case that the user selects the correct value, there seems little point in using a Select Case statement at all. The cardinal rule should be to use whichever makes your code the clearest and easiest to understand. There's little validity to the suspicion that Select Case is faster than an If statement—the compiler is smart enough to produce virtually equivalent results in almost every case.

Upvotes: 12

Stefan
Stefan

Reputation: 11509

I often combine SELECT/CASE with IF/END IF. The first one to catch a range, then second one to do similar things with the range, but maybe with small differences.

    Dim Result As Integer = 1
    Select Case Result
        Case 0 To 3
            SaveOrder()
            '0 to 3 is success 
            If Result <> 0 AndAlso Result <> 3 Then
                '1 and 2 = Everything ok
                SendCustomerMesage(0)
            Else
                '0 and 3 = Order OK, but no stock in storage
                SendCustomerMesage(1)
            End If

        Case 4 To 8
            '4 to 8 is error 
            InformCustomer(value)
        Case Else
            HandleError(value)
    End Select

Upvotes: 0

Ando
Ando

Reputation: 11409

Building on what Cody wrote I would go with:

Select Case value
    Case 1, 2
        DoWork()
    Case 0 ,3               
        'nothing to do, only log if needed
    Case Else
        Debug.Fail("Please provide a logical path for all possible values")
End Select

The extra branches are just to clarify the intent of the code and to guard against future changes.

Upvotes: 2

Related Questions