By: Ramlak in VB.net Tutorials on 2008-11-25
The For loop is probably the most popular of all Visual Basic loops. The Do loop doesn't need aloop index, but the For loop does; a loop index counts the number of loop iterations as the loop executes. Here's the syntax for the For loop-note that you can terminate a For loop at any time with Exit For:
For index = start To end [Step step] [statements] [Exit For] [statements] Next [index]
The index variable is originally set to start automatically when the loop begins. Each time through the loop, index is incremented by step (step is set to a default of 1 if you don't specify a value) and when index equals end, the loop ends.
Here's how to put this loop to work; in this case, I'm displaying "Hello from Visual Basic" four times (that is, intLoopIndex will hold 0 the first time; 1, the next; followed by 2; and then 3, at which point the loop terminates):
Module Module1 Sub Main() Dim intLoopIndex As Integer For intLoopIndex = 0 To 3 System.Console.WriteLine("Hello from Visual Basic") Next intLoopIndex End Sub End Module
Here's what you see when you run this code:
Hello from Visual Basic Hello from Visual Basic Hello from Visual Basic Hello from Visual Basic Press any key to continue
If I were to use a step size of 2:
For intLoopIndex = 0 To 3 Step 2 System.Console.WriteLine("Hello from Visual Basic") Next intLoopIndex
I'd see this result:
Hello from Visual Basic Hello from Visual Basic Press any key to continue
Although it's been common practice to use a loop index after a loop completes (to see how many loop iterations were executed), that practice is now discouraged by people who make it their business to write about good and bad programming practices.
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