VB.NET For Loops

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Arrow indicates looping

A loop executes statements repeatedly. It often has an upper and lower bound. The For-loop proceeds through a range of values. A step indicates the progression.
Other loops,
such as While,
continue until a condition is met.

Loops

Important

Here are the looping constructs in the VB.NET language. The For Each construct is probably the least error-prone but is not always available. We also show examples of the For-loop construct directly on this page.

For EachWhileDo WhileDo Until

For

For loop

This example uses the lower bound 0 and the upper bound 5 in the For-loop statement. Please remember that the two bounds are inclusive, meaning all the numbers including 0 and 5 will be reached.

Tip:In this example, we see the Exit For statement. This statement breaks out of the enclosing For-loop.

Tip 2:Exit works in all loops and Subs.
Please see the detailed information about Exit.

Exit Statements
Program that uses For: VB.NET

Module Module1
    Sub Main()
	' This loop goes from 0 to 5.
	For value As Integer = 0 To 5
	    ' Exit condition if the value is three.
	    If (value = 3) Then
		Exit For
	    End If
	    Console.WriteLine(value)
	Next
    End Sub
End Module

Output

0
1
2

For Step

Steps

In this example, we want to decrement the counter variable instead of increment it. In other words, we go down not up. We start at 10 and then continue down in steps of 2 to 0. We print the value in each iteration.

Also:The Step keyword is used near the end of the For-statement and it is the delta each loop iteration will have.

So:If you want to decrement by 1 each time, you can use -1.
If you want to increment by 1, use 1.

Program that uses For Step: VB.NET

Module Module1
    Sub Main()
	' This loop uses Step to go down 2 each iteration.
	For value As Integer = 10 To 0 Step -2
	    Console.WriteLine(value)
	Next
    End Sub
End Module

Output

10
8
6
4
2
0

String loops

String type

The For and For Each loops can be used on String variables. This gives us a way to check or process each character in the Object data. String loops are an alternative to using Regex for modifying and creating Strings.

Loop Over StringRegex.Replace

Summary

Keyword: keywords direct program behavior

The For-loop is one of the core looping constructs in the VB.NET language. It provides a way to explicitly specify the loop bounds. Because of this, it often leads to more robust code.

And:With the for-keyword, fewer careless bugs caused by incorrect loop boundaries may occur in programs.

VB.NET