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Array.Sort Method (Array, Array, IComparer)

Sorts a pair of one-dimensional Array objects (one contains the keys and the other contains the corresponding items) based on the keys in the first Array using the specified IComparer.

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

public static void Sort(
	Array keys,
	Array items,
	IComparer comparer
)

Parameters

keys
Type: System.Array
The one-dimensional Array that contains the keys to sort.
items
Type: System.Array
The one-dimensional Array that contains the items that correspond to each of the keys in the keys Array.
-or-
null to sort only the keys Array.
comparer
Type: System.Collections.IComparer
The IComparer implementation to use when comparing elements.
-or-
null to use the IComparable implementation of each element.

ExceptionCondition
ArgumentNullException

keys is null.

RankException

The keys Array is multidimensional.

-or-

The items Array is multidimensional.

ArgumentException

items is not null, and the length of keys is greater than the length of items.

-or-

The implementation of comparer caused an error during the sort. For example, comparer might not return 0 when comparing an item with itself.

InvalidOperationException

comparer is null, and one or more elements in the keys Array do not implement the IComparable interface.

Each key in the keys Array has a corresponding item in the items Array. When a key is repositioned during the sorting, the corresponding item in the items Array is similarly repositioned. Therefore, the items Array is sorted according to the arrangement of the corresponding keys in the keys Array.

If comparer is null, each key in the keys Array must implement the IComparable interface to be capable of comparisons with every other key.

You can sort if there are more items than keys, but the items that have no corresponding keys will not be sorted. You cannot sort if there are more keys than items; doing this throws an ArgumentException.

If the sort is not successfully completed, the results are undefined.

This method uses the QuickSort algorithm. This implementation performs 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.

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

The following example shows how to sort two associated arrays where the first array contains the keys and the second array contains the values. Sorts are done using the default comparer and a custom comparer that reverses the sort order. Note that the result might vary depending on the current CultureInfo.


using System;
using System.Collections;

public class SamplesArray  {

   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 Array and a new custom comparer.
      String[] myKeys = { "red", "GREEN", "YELLOW", "BLUE", "purple", "black", "orange" };
      String[] myValues = { "strawberries", "PEARS", "LIMES", "BERRIES", "grapes", "olives", "cantaloupe" };
      IComparer myComparer = new myReverserClass();

      // Displays the values of the Array.
      Console.WriteLine( "The Array initially contains the following values:" );
      PrintKeysAndValues( myKeys, myValues );

      // Sorts a section of the Array using the default comparer.
      Array.Sort( myKeys, myValues, 1, 3 );
      Console.WriteLine( "After sorting a section of the Array using the default comparer:" );
      PrintKeysAndValues( myKeys, myValues );

      // Sorts a section of the Array using the reverse case-insensitive comparer.
      Array.Sort( myKeys, myValues, 1, 3, myComparer );
      Console.WriteLine( "After sorting a section of the Array using the reverse case-insensitive comparer:" );
      PrintKeysAndValues( myKeys, myValues );

      // Sorts the entire Array using the default comparer.
      Array.Sort( myKeys, myValues );
      Console.WriteLine( "After sorting the entire Array using the default comparer:" );
      PrintKeysAndValues( myKeys, myValues );

      // Sorts the entire Array using the reverse case-insensitive comparer.
      Array.Sort( myKeys, myValues, myComparer );
      Console.WriteLine( "After sorting the entire Array using the reverse case-insensitive comparer:" );
      PrintKeysAndValues( myKeys, myValues );

   }

   public static void PrintKeysAndValues( String[] myKeys, String[] myValues )  {
      for ( int i = 0; i < myKeys.Length; i++ )  {
         Console.WriteLine( "   {0,-10}: {1}", myKeys[i], myValues[i] );
      }
      Console.WriteLine();
   }
}


/* 
This code produces the following output.

The Array initially contains the following values:
   red       : strawberries
   GREEN     : PEARS
   YELLOW    : LIMES
   BLUE      : BERRIES
   purple    : grapes
   black     : olives
   orange    : cantaloupe

After sorting a section of the Array using the default comparer:
   red       : strawberries
   BLUE      : BERRIES
   GREEN     : PEARS
   YELLOW    : LIMES
   purple    : grapes
   black     : olives
   orange    : cantaloupe

After sorting a section of the Array using the reverse case-insensitive comparer:
   red       : strawberries
   YELLOW    : LIMES
   GREEN     : PEARS
   BLUE      : BERRIES
   purple    : grapes
   black     : olives
   orange    : cantaloupe

After sorting the entire Array using the default comparer:
   black     : olives
   BLUE      : BERRIES
   GREEN     : PEARS
   orange    : cantaloupe
   purple    : grapes
   red       : strawberries
   YELLOW    : LIMES

After sorting the entire Array using the reverse case-insensitive comparer:
   YELLOW    : LIMES
   red       : strawberries
   purple    : grapes
   orange    : cantaloupe
   GREEN     : PEARS
   BLUE      : BERRIES
   black     : olives

*/



.NET Framework

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

.NET Framework Client Profile

Supported in: 4, 3.5 SP1

Windows 7, Windows Vista SP1 or later, Windows XP SP3, Windows XP SP2 x64 Edition, Windows Server 2008 (Server Core not supported), Windows Server 2008 R2 (Server Core supported with SP1 or later), Windows Server 2003 SP2

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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