ArrayList.Sort Method (Int32, Int32, IComparer)

Sorts the elements in a range of elements in ArrayList using the specified comparer.

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

public virtual void Sort(
	int index,
	int count,
	IComparer comparer
)

Parameters

index
Type: System.Int32

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

count
Type: System.Int32

The length of the range to sort.

comparer
Type: System.Collections.IComparer

The IComparer implementation to use when comparing elements.

-or-

A null reference (Nothing in Visual Basic) to use the IComparable implementation of each element.

ExceptionCondition
ArgumentOutOfRangeException

index is less than zero.

-or-

count is less than zero.

ArgumentException

index and count do not specify a valid range in the ArrayList.

NotSupportedException

The ArrayList is read-only.

InvalidOperationException

An error occurred while comparing two elements.

If comparer is set to null, this method performs a comparison sort (also called an unstable sort); that is, if two elements are equal, their order might not be preserved. In contrast, a stable sort preserves the order of elements that are equal. To perform a stable sort, you must implement a custom IComparer interface.

On average, this method is an O(n log n) operation, where n is count; in the worst case it is an O(n^2) operation.

The following code example shows how to sort the values in a range of elements in an ArrayList using the default comparer and a custom comparer that reverses the sort order.

using System;
using System.Collections;

public class SamplesArrayList  {

   public class myReverserClass : IComparer  {

      // Calls CaseInsensitiveComparer.Compare with the parameters reversed. 
      int IComparer.Compare( Object x, Object y )  {
          return( (new CaseInsensitiveComparer()).Compare( y, x ) );
      }

   }

   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( "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 );

      // Sorts the values of the ArrayList using the default comparer.
      myAL.Sort( 1, 3, null );
      Console.WriteLine( "After sorting from index 1 to index 3 with the default comparer:" );
      PrintIndexAndValues( myAL );

      // Sorts the values of the ArrayList using the reverse case-insensitive comparer.
      IComparer myComparer = new myReverserClass();
      myAL.Sort( 1, 3, myComparer );
      Console.WriteLine( "After sorting from index 1 to index 3 with the reverse case-insensitive comparer:" );
      PrintIndexAndValues( myAL );

   }

   public static void PrintIndexAndValues( IEnumerable myList )  {
      int i = 0;
      foreach ( Object obj in myList )
         Console.WriteLine( "\t[{0}]:\t{1}", i++, obj );
      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 sorting from index 1 to index 3 with the default comparer:
        [0]:    The
        [1]:    BROWN
        [2]:    FOX
        [3]:    QUICK
        [4]:    jumped
        [5]:    over
        [6]:    the
        [7]:    lazy
        [8]:    dog

After sorting from index 1 to index 3 with the reverse case-insensitive comparer:
        [0]:    The
        [1]:    QUICK
        [2]:    FOX
        [3]:    BROWN
        [4]:    jumped
        [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
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