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ArrayList.Reverse Method (Int32, Int32)

Reverses the order of the elements in the specified range.

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

public virtual void Reverse(
	int index,
	int count
)

Parameters

index
Type: System.Int32

The zero-based starting index of the range to reverse.

count
Type: System.Int32

The number of elements in the range to reverse.

ExceptionCondition
ArgumentOutOfRangeException

index is less than zero.

-or-

count is less than zero.

ArgumentException

index and count do not denote a valid range of elements in the ArrayList.

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 a range of elements 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( 1, 3 );

      // 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:
   The
   FOX
   BROWN
   QUICK
   jumps
   over
   the
   lazy
   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
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