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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

.NET Framework Client Profile

Supported in: 4, 3.5 SP1

XNA Framework

Supported in: 3.0, 2.0, 1.0

Portable Class Library

Supported in: Portable Class Library

Supported in: Windows Phone 8.1

Supported in: Windows Phone Silverlight 8.1

Supported in: Windows Phone Silverlight 8
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