Seeking Variable Scope Advice

[JDYoder]

I understand the scope of a variable remains within its block of code. For instance, this var cannot be access outside the If block...

 

If [Condition]
  Dim i As Integer
  ...
End If

 

Same with a loop like this...

 

While [Condition]
  Dim i As Integer
  ...
End While

 

However, I'm wondering if the second example is bad practice. I like having it declared within the block since that's the only place it's used. However, since it's in a looping block, I'm wondering if the var is created and destructed on every pass, and I should instead declare it before the loop. Thanks for your input.

[IceAzul]

The variable is created on the stack when you enter the function. What you have here is a scope issue. Outside the loop, the code cannot access that particular variable.

 

Lets say you have a function like this:

Sub A()

   Dim X As Integer

   For X = 0 to 100

       Dim Y As Integer

   Next

End Sub

 

At the beginning of the function, both X and Y are created.

 

 

This is only true of value types(such as Integer, Byte, etc), however.

 

If you are doing this with Reference types (such as StringBuilders, ArrayLists, etc), it will create a new object each time, and thus should be avoided.

Edited August 17, 2005 by IceAzul