In today’s lesson, I’ll show you how to use Conditional Statements in VbScript. Conditional statements are very important in any programming, so it is in VBScripting. We have a choice of 2 statements in VBScript If..Then...Else and Select...Case.

If…then

If you want to execute a set of instructions only when a certain condition is met, you can use an If…then condition. You can control the execution of instructions based on a true condition, as follows:

if condition = True Then

A = B

End If

You can also use this form:
if Not condition Then

A <> B

End If

You can extend the If…then condition with the Else and ElseIf statements. The Else statement offers an alternative when a condition you specified isn't met. Here's the structure of an if…then…else condition:

if homeRun = True Then

Msgbox "The condition has been met."

Else

Msgbox "The condition has not been met."

End If

To add more conditions, you can use the ElseIf statement. In this way, each condition you add to the code is checked for validity. Here's an example that uses the ElseIf statement:

if firstValue < 0 Then

Msgbox "The value is less than zero."

ElseIf firstValue = 0 Then

Msgbox "The value is equal to zero."

ElseIf firstValue = 1 Then

Msgbox "The value is equal to one."

ElseIf firstValue = 2 Then

Msgbox "The value is equal to two."

Else

Msgbox "The value is greater than 4."

End If

Select Case

Checking for multiple conditions with the ElseIf structure can be tedious. When you want to check more than three conditions, you should probably use the Select Case statement. In the Select Case structure, the last example in the previous section can be transformed into code that's clearer and easier to understand:

Select Case firstValue

Case < 0

Msgbox "The value is less than zero."

Case 0

Msgbox "The value is equal to zero."

Case 1

Msgbox "The value is equal to one."

Case 2

Msgbox "The value is equal to two."

Case 3

Msgbox "The value is equal to three."

Case 4

Msgbox "The value is equal to four."

End Select

If you compare the ElseIf example and the Select Case example, you can see that the Select Case example requires less code and has a simpler structure. You can apply this same structure any time you want to check for multiple conditions. Here's another example of Select Case:

Select Case Abbrev

Case "HTML"

Message "The HyperText Markup Language."

Case "SGML"

Message "The Standard Generalized Markup Language."

Case "VRML"

Message "The Virtual Reality Modeling Language."

Case Else

Message "You have entered an abbreviation not known to the system."

End Select