Entry

Does Visual Basic have "short-circuit" boolean evaluation like in Java and C++?

Mar 21st, 2001 14:46
Mike Ogilvie, Joe T,

Short Answer: No
Long Answer:
Let's make sure we're defining "short-circuit" the same way. Take this 
section of code...
    If (Not IsEmpty(vObject)) And (vObject.Name = "DataList") Then
        vObject.DoSomething
    End If
The idea here would be to first make sure that there's actually 
something in vObject. If there is, then to make sure it's the correct 
name. In the above If statement, it would check the first condition, 
find out that it fails, and then "short-circuit" the process by not 
bothering to check any remaining conditions.
Visual Basic does not do this. It evaluates everything in the line of 
code, regardless if it logically needs to or not. So in VB, the above 
code should be written...
    If Not IsEmpty(vObject) Then
        If vObject.Name = "DataList" Then
            vObject.DoSomething
        End If
    End If
More of a hassle, I know. But these situations don't come around too 
often. If they do, you can probably architect the application to handle 
it more efficiently.