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Array.Reverse Method (Array, Int32, Int32)

Reverses the sequence of the elements in a range of elements in the one-dimensional Array.

Namespace:  System
Assembly:  mscorlib (in mscorlib.dll)

'Declaration
Public Shared Sub Reverse ( _
	array As Array, _
	index As Integer, _
	length As Integer _
)

Parameters

array
Type: System.Array

The one-dimensional Array to reverse.

index
Type: System.Int32

The starting index of the section to reverse.

length
Type: System.Int32

The number of elements in the section to reverse.

ExceptionCondition
ArgumentNullException

array is Nothing.

RankException

array is multidimensional.

ArgumentOutOfRangeException

index is less than the lower bound of array.

-or-

length is less than zero.

ArgumentException

index and length do not specify a valid range in array.

After a call to this method, the element at myArray[i], where i is any index in the array, moves to myArray[j], where j equals (myArray.Length + myArray.GetLowerBound(0)) - (i - myArray.GetLowerBound(0)) - 1.

The Reverse method can be used to reverse a jagged array.

This method is an O(n) operation, where n is length.

The following code example shows how to reverse the sort of the values in a range of elements in an Array.

Imports System
Imports Microsoft.VisualBasic

Public Class SamplesArray    

    Public Shared Sub Main()

        ' Creates and initializes a new Array. 
        Dim myArray As Array = Array.CreateInstance(GetType(String), 9)
        myArray.SetValue("The", 0)
        myArray.SetValue("QUICK", 1)
        myArray.SetValue("BROWN", 2)
        myArray.SetValue("FOX", 3)
        myArray.SetValue("jumps", 4)
        myArray.SetValue("over", 5)
        myArray.SetValue("the", 6)
        myArray.SetValue("lazy", 7)
        myArray.SetValue("dog", 8)

        ' Displays the values of the Array.
        Console.WriteLine("The Array initially contains the " _
           + "following values:")
        PrintIndexAndValues(myArray)

        ' Reverses the sort of the values of the Array.
        Array.Reverse(myArray, 1, 3)

        ' Displays the values of the Array.
        Console.WriteLine("After reversing:")
        PrintIndexAndValues(myArray)
    End Sub     


    Public Shared Sub PrintIndexAndValues(myArray As Array)
        Dim i As Integer 
        For i = myArray.GetLowerBound(0) To myArray.GetUpperBound(0)
            Console.WriteLine(ControlChars.Tab + "[{0}]:" + ControlChars.Tab _
               + "{1}", i, myArray.GetValue(i))
        Next i
    End Sub 
End Class 

' This code produces the following output. 
'  
' The Array initially contains the following values: 
'     [0]:    The 
'     [1]:    QUICK 
'     [2]:    BROWN 
'     [3]:    FOX 
'     [4]:    jumps 
'     [5]:    over 
'     [6]:    the 
'     [7]:    lazy 
'     [8]:    dog 
' After reversing: 
'     [0]:    The 
'     [1]:    FOX 
'     [2]:    BROWN 
'     [3]:    QUICK 
'     [4]:    jumps 
'     [5]:    over 
'     [6]:    the 
'     [7]:    lazy 
'     [8]:    dog 

.NET Framework

Supported in: 4.6, 4.5, 4, 3.5, 3.0, 2.0, 1.1, 1.0

.NET Framework Client Profile

Supported in: 4, 3.5 SP1

Portable Class Library

Supported in: Portable Class Library

.NET for Windows Store apps

Supported in: Windows 8

Supported in: Windows Phone 8.1

Supported in: Windows Phone Silverlight 8.1

Supported in: Windows Phone Silverlight 8

Windows Phone 8.1, Windows Phone 8, Windows 8.1, Windows Server 2012 R2, Windows 8, Windows Server 2012, Windows 7, Windows Vista SP2, Windows Server 2008 (Server Core Role not supported), Windows Server 2008 R2 (Server Core Role supported with SP1 or later; Itanium not supported)

The .NET Framework does not support all versions of every platform. For a list of the supported versions, see .NET Framework System Requirements.

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