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ArrayList.Reverse Method ()

Reverses the order of the elements in the entire ArrayList.

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

public virtual void Reverse ()
public void Reverse ()
public function Reverse ()
Not applicable.

Exception typeCondition

NotSupportedException

The ArrayList is read-only.

This method uses Array.Reverse to reverse the order of the elements, such that the element at ArrayList [i], where i is any index within the range, moves to ArrayList [j], where j equals index + index + count - i - 1.

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

The following code example shows how to reverse the sort order of the values in an ArrayList.

using System;
using System.Collections;
public class SamplesArrayList  {

   public static void Main()  {

      // Creates and initializes a new ArrayList.
      ArrayList myAL = new ArrayList();
      myAL.Add( "The" );
      myAL.Add( "quick" );
      myAL.Add( "brown" );
      myAL.Add( "fox" );
      myAL.Add( "jumps" );
      myAL.Add( "over" );
      myAL.Add( "the" );
      myAL.Add( "lazy" );
      myAL.Add( "dog" );

      // Displays the values of the ArrayList.
      Console.WriteLine( "The ArrayList initially contains the following values:" );
      PrintValues( myAL );

      // Reverses the sort order of the values of the ArrayList.
      myAL.Reverse();

      // Displays the values of the ArrayList.
      Console.WriteLine( "After reversing:" );
      PrintValues( myAL );
   }

   public static void PrintValues( IEnumerable myList )  {
      foreach ( Object obj in myList )
         Console.WriteLine( "   {0}", obj );
      Console.WriteLine();
   }

}


/* 
This code produces the following output.

The ArrayList initially contains the following values:
   The
   quick
   brown
   fox
   jumps
   over
   the
   lazy
   dog

After reversing:
   dog
   lazy
   the
   over
   jumps
   fox
   brown
   quick
   The
*/ 

import System.*;
import System.Collections.*;

public class SamplesArrayList
{
    public static void main(String[] args)
    {
        // Creates and initializes a new ArrayList.
        ArrayList myAL = new ArrayList();

        myAL.Add("The");
        myAL.Add("quick");
        myAL.Add("brown");
        myAL.Add("fox");
        myAL.Add("jumps");
        myAL.Add("over");
        myAL.Add("the");
        myAL.Add("lazy");
        myAL.Add("dog");

        // Displays the values of the ArrayList.
        Console.WriteLine("The ArrayList initially contains the" 
            + " following values:");
        PrintValues(myAL);

        // Reverses the sort order of the values of the ArrayList.
        myAL.Reverse();

        // Displays the values of the ArrayList.
        Console.WriteLine("After reversing:");
        PrintValues(myAL);
    } //main

    public static void PrintValues(IEnumerable myList)
    {
        IEnumerator objMyEnum = myList.GetEnumerator();
        while (objMyEnum.MoveNext()) {
            Object obj = objMyEnum.get_Current();
            Console.WriteLine("   {0}", obj);
        }
        Console.WriteLine();
    } //PrintValues
} //SamplesArrayList 

/* 
 This code produces the following output.
 
 The ArrayList initially contains the following values:
    The
    quick
    brown
    fox
    jumps
    over
    the
    lazy
    dog

 After reversing:
    dog
    lazy
    the
    over
    jumps
    fox
    brown
    quick
    The
 */

import System;
import System.Collections;

// Creates and initializes a new ArrayList.
var myAL : ArrayList = new ArrayList();
myAL.Add( "The" );
myAL.Add( "quick" );
myAL.Add( "brown" );
myAL.Add( "fox" );
myAL.Add( "jumped" );
myAL.Add( "over" );
myAL.Add( "the" );
myAL.Add( "lazy" );
myAL.Add( "dog" );

// Displays the values of the ArrayList.
Console.WriteLine( "The ArrayList initially contains the following values:" );
PrintIndexAndValues( myAL );

// Reverses the sort order of the values of the ArrayList.
myAL.Reverse();

// Displays the values of the ArrayList.
Console.WriteLine( "After reversing:" );
PrintIndexAndValues( myAL );

 
function PrintIndexAndValues( myList : IEnumerable )  {
   var i : int = 0;
   var myEnumerator : System.Collections.IEnumerator  = myList.GetEnumerator();
   while ( myEnumerator.MoveNext() )
      Console.WriteLine( "\t[{0}]:\t{1}", i++, myEnumerator.Current );
   Console.WriteLine();
}
 /* 
 This code produces the following output.
 
 The ArrayList initially contains the following values:
     [0]:    The
     [1]:    quick
     [2]:    brown
     [3]:    fox
     [4]:    jumped
     [5]:    over
     [6]:    the
     [7]:    lazy
     [8]:    dog
 
 After reversing:
     [0]:    dog
     [1]:    lazy
     [2]:    the
     [3]:    over
     [4]:    jumped
     [5]:    fox
     [6]:    brown
     [7]:    quick
     [8]:    The
 */ 

Windows 98, Windows Server 2000 SP4, Windows CE, Windows Millennium Edition, Windows Mobile for Pocket PC, Windows Mobile for Smartphone, Windows Server 2003, Windows XP Media Center Edition, Windows XP Professional x64 Edition, Windows XP SP2, Windows XP Starter Edition

The Microsoft .NET Framework 3.0 is supported on Windows Vista, Microsoft Windows XP SP2, and Windows Server 2003 SP1.

.NET Framework

Supported in: 3.0, 2.0, 1.1, 1.0

.NET Compact Framework

Supported in: 2.0, 1.0

XNA Framework

Supported in: 1.0

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