Select case statement- working with variables VB.NET - vb.net

Question

Good day! I'm new to this control structure so what I'm trying to figure out are the ways to get values of input1 and input2 FROM EACH CASES( Case "String1" and Case "String2") and use it in Case "String3".
Code:
Dim input1 As String
Dim input2 As String
Select Case sampleVariable
Case "String1"
input1 = "Some value"
Case "String2"
input2 = "Some value"
Case "String3"
MsgBox(input1 & input 2)
End Select
Thank you.

Answer 1

Essentially, a select statements is like a shorthand for a significant amount of IF...THEN...ELSEIF...END If statements. All it really does is make the code easier to read if you have a significant amount of IF statements or conditions that need to be tested against a single instance. Mostly Select statemnts will be used to determine the outcome of some dialogue box, or other which predefined outcome was chosed by the user. if you were to write out your select statement, it would look like this:
If sampleVariable.Equals("String1") Then
input1 = "Some value"
ElseIf sampleVariable.Equals("String2") Then
input2 = "Some value"
ElseIf sampleVariable.Equals("String3") Then
MsgBox(input1 & input2)
End if
The reason you can't access the values that you are setting from the first two statements in the third case, is because the value assignment is hiding in an enclosed block. To see this more clearly, take a look at this:
Dim checkValue As Boolean
If checkValue Then
Dim hiddenVariable As String = "Hello World"
End If
MsgBox(hiddenVariable)
Using the above example, my hiddenVarible is declared and instantiated within the If block. This would work out fine as long as checkValue were always true. However if checkValue were false then hiddenVariable would never declared and you would probably receive an exception about a NullReference exception. In fact, Visual Studio won't even compile that under default settings.
The same type of thing is happening to your code as well. while you have declared input1 and input2 in the beginning, you haven't instantiated them with any values. So if case #3 is the outcome of you select statement, then you are essentially calling out MsgBox(Nothing & Nothing). The settings of values from your first two case statements never happen because the case statement didn't evaluate to true.
Now looking at the code, I'm not sure why you're going through about it this way since you are assigning string literals to your variables. I'm going to put down a few alternative options for you to choose from.
Adding some checks to case #3 for Nothing values:
Dim input1 As String
Dim input2 As String
Select Case sampleVariable
Case "String1"
input1 = "Some value"
Case "String2"
input2 = "Some value"
Case "String3"
If IsNothing(input1) OrElse IsNothing(input2) Then
MsgBox("At least one of the input values has no value")
Else
MsgBox(input1 & input2)
End If
End Select
Use the classic IF...THEN...END IF blocks:
Dim input1 As String = String.Empty
Dim input2 As String = String.Empty
If sampleVariable.Equals("String1") Then
input1 = "Some value"
ElseIf sampleVariable.Equals("String2") Then
input2 = "Some value"
ElseIf sampleVariable.Equals("String3") Then
MsgBox(input1 & input2)
End if
Assign the values upfront and forget the select statement because it really isn't doing anything:
Dim input1 As String = "Some value"
Dim input2 As String = "Some value"
If sampleVariable.Equals("String3") Then MsgBox(input1 & input2)
I hope this get you towards what ever answer you were looking for. H
owever if you were to give more background on what you are trying to do exactly and why you were trying to accomplish it this way, we may be able to help better.

Answer 2

I don't understand what you trying to do, but first what come in mind:
Dim input1 As String
Dim input2 As String
If sampleVariable.Equals("String1") = True Then
input1 = "Some value"
End if
If sampleVariable.Equals("String2") = True Then
input2 = "Some value"
End if
If sampleVariable.Equals("String3") = True Then
MsgBox(input1 & input2)
End if