VB.NET Array.Reverse Example

Use the Array.Reverse subroutine to invert the order of elements.

Array.Reverse inverts the order of elements. It can act upon an entire array, or just part of an array (a range). It can be used to sort in reverse—simply call Reverse after Sort.Array

An example. Let's begin with this program. The initial array is pointed to by the reference variable a. Then, we reverse that array with Array.Reverse(a). The return value is not used.Integer

Finally: We reverse only the first two elements by using the parameters 0 (the first index) and 2 (the count of elements to reverse).

Tip: Reverse is found on the Array type. It is a static (shared) function. We call it with a composite name.

Shared

VB.NET program that reverses array Module Module1 Sub Main() Dim a() As Integer = {1, 4, 6, 10} For Each v As Integer In a Console.WriteLine(v) Next Console.WriteLine() ' Reverse entire array. Array.Reverse(a) For Each v As Integer In a Console.WriteLine(v) Next Console.WriteLine() ' Reverse part of array. Array.Reverse(a, 0, 2) For Each v As Integer In a Console.WriteLine(v) Next End Sub End Module Output 1 4 6 10 10 6 4 1 6 10 4 1

A discussion. The implementation of .NET methods is relevant because it tells us whether they will be efficient. Array.Reverse calls an internal method called TrySZReverse.

Tip: This is in unmanaged code. It is likely faster in most situations because of unmanaged optimizations.

Reverse string. With Array.Reverse we can reverse the ordering of chars in a string. We first use ToCharArray to convert a string to a char array.Reverse String

A summary. We reverse an entire array or only parts (ranges) of an array with Array.Reverse. The type of the elements in the array are not important—they are not sorted or changed.

An internal method. Array.Reverse uses an internal, optimized method. It would be hard to develop a faster one in VB.NET code. Usually this built-in is preferred.