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.
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 ModuleFOR 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.
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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.