Loop Over String Array
This page was last reviewed on Nov 28, 2023.
Dot Net Perls
Loop, String array. Suppose you have a String array in your VB.NET program, and want to loop over its elements. This can be done in various ways in this language.
A For Each loop is the clearest and least error-prone, but other loops like For may be more useful in some programs. A For Step loop can be used to loop in reverse.
Example. To begin, we need to have a String array for our various loops. We use array initializer syntax to create a String array of 4 elements.
Step 1 We use the For Each loop over the "array1" elements. We use string interpolation syntax to print each element to the console.
Step 2 We loop over the indexes of the array with a For-loop. We go to the Length minus 1, so avoid reading past the end.
Step 3 We can also use For To loops to iterate backwards—we must specify a Step of -1.
Step 4 Here is a functional version of For Each—we call a Sub on each element in the array with Array.ForEach.
Module Module1 Sub Main(args as String()) Dim array1() As String = {"one", "two", "three", "four"} ' Step 1: loop over the array with For Each. For Each value in array1 Console.WriteLine($"FOR EACH: {value}") Next ' Step 2: loop over the array with For. For i = 0 To array1.Length - 1 Dim value as String = array1(i) Console.WriteLine($"FOR: {value}") Next ' Step 3: loop over the string array backwards. For i = array1.Length - 1 To 0 Step -1 Dim value = array1(i) Console.WriteLine($"BACKWARDS: {value}") Next ' Step 4: loop with Array.ForEach subroutine with a lambda. Array.ForEach(array1, Sub(value As String) Console.WriteLine($"ForEach: {value}") End Sub) End Sub End Module
FOR EACH: one FOR EACH: two FOR EACH: three FOR EACH: four FOR: one FOR: two FOR: three FOR: four BACKWARDS: four BACKWARDS: three BACKWARDS: two BACKWARDS: one ForEach: one ForEach: two ForEach: three ForEach: four
Summary. String arrays, like other arrays in VB.NET, can be looped over in several ways. We can use For loops, or even the Array.ForEach subroutine to call a subroutine repeatedly.
Dot Net Perls is a collection of tested code examples. Pages are continually updated to stay current, with code correctness a top priority.
Sam Allen is passionate about computer languages. In the past, his work has been recommended by Apple and Microsoft and he has studied computers at a selective university in the United States.
This page was last updated on Nov 28, 2023 (new).
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