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Friday 20 April 2012

ASP Select Case

ASP Select Case

In the previous lesson you learned how to setup a block of If Statements using the ElseIf keyword, but this is not the most efficient method for checking multiple conditions. ASP uses the Select Case statement to check for multiple Is Equal To "=" conditions of a single variable.


If you are an experienced programmer you realize the Select statement resembles a Switch statement that other programming languages use for an efficient way to check a large number of conditions at one time.

ASP Select Case Example

The variable that appears immediately after Select Case is what will be checked against the list of case statements. These case statements are contained within the Select Case block of code. Below is an ASP Select Case example that only checks for integer values. Later we will show how to check for strings.

ASP Code:

<%
Dim myNum
myNum = 5
Select Case myNum
 Case 2
  Response.Write("myNum is Two")
 Case 3
  Response.Write("myNum is Three")
 Case 5
  Response.Write("myNum is Five")
 Case Else
  Response.Write("myNum is " & myNum) 
End Select
%>

Display:

myNum is Five

ASP Select Case - Case Else

In the last example you might have noticed something strange, there was a case that was referred to as "Case Else". This case is actually a catch all option for every case that does not fit into the defined cases. In english it might be thought of as: If all these cases don't match then I'll use the "Case Else"!
It is a good programming practice to always include the catch all Else case. Below we have an example that always executes the Else case.

ASP Code:

<%
Dim myNum
myNum = 454
Select Case myNum
 Case 2
  Response.Write("myNum is Two")
 Case 3
  Response.Write("myNum is Three")
 Case 5
  Response.Write("myNum is Five")
 Case Else
  Response.Write("myNum is " & myNum) 
End Select
%>

Display:

myNum is 454

Select Case with String Variables

So far we have only used integers in our Select Case statements, but you can also use a string as the variable to be used in the statement. Below we Select against a string.

ASP Code:

<%
Dim myPet
myPet = "cat"
Select Case myPet
 Case "dog"
  Response.Write("I own a dog")
 Case "cat"
  Response.Write("I do not own a cat")
 Case Else
  Response.Write("I once had a cute goldfish")
End Select
%>

Display:

I do not own a cat

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