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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)

'Declaration
Public Shared Sub Sort ( _
	keys As Array, _
	items As Array, _
	comparer As IComparer _
)
'Usage
Dim keys As Array
Dim items As Array
Dim comparer As IComparer

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

Parameters

keys

The one-dimensional Array that contains the keys to sort.

items

The one-dimensional Array that contains the items that correspond to each of the keys in the keysArray.

-or-

a null reference (Nothing in Visual Basic) to sort only the keysArray.

comparer

The IComparer implementation to use when comparing elements.

-or-

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

Exception typeCondition

ArgumentNullException

keys is a null reference (Nothing in Visual Basic).

RankException

The keysArray is multidimensional.

-or-

The itemsArray is multidimensional.

ArgumentException

items is not a null reference (Nothing in Visual Basic), and the lower bound of keys does not match the lower bound of items.

-or-

items is not a null reference (Nothing in Visual Basic), and the length of keys does not match 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 a null reference (Nothing in Visual Basic), and one or more elements in the keysArray do not implement the IComparable interface.

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

If comparer is a null reference (Nothing in Visual Basic), each key in the keysArray must implement the IComparable interface to be capable of comparisons with every other key.

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.

Imports System
Imports System.Collections

Public Class SamplesArray

   Public Class myReverserClass
      Implements IComparer

      ' Calls CaseInsensitiveComparer.Compare with the parameters reversed.
      Function Compare(x As [Object], y As [Object]) As Integer _
         Implements IComparer.Compare
         Return New CaseInsensitiveComparer().Compare(y, x)
      End Function 'IComparer.Compare

   End Class 'myReverserClass


   Public Shared Sub Main()

      ' Creates and initializes a new Array and a new custom comparer.
      Dim myKeys As [String]() =  {"red", "GREEN", "YELLOW", "BLUE", "purple", "black", "orange"}
      Dim myValues As [String]() =  {"strawberries", "PEARS", "LIMES", "BERRIES", "grapes", "olives", "cantaloupe"}
      Dim 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)

   End Sub 'Main


   Public Shared Sub PrintKeysAndValues(myKeys() As [String], myValues() As [String])

      Dim i As Integer
      For i = 0 To myKeys.Length - 1
         Console.WriteLine("   {0,-10}: {1}", myKeys(i), myValues(i))
      Next i
      Console.WriteLine()

   End Sub 'PrintKeysAndValues

End Class 'SamplesArray


'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


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

public class SamplesArray
{
    public static class MyReverserClass implements IComparer
    {
        // Calls CaseInsensitiveComparer.Compare with the parameters reversed.
        public int Compare(Object x, Object y)
        {
            return (new CaseInsensitiveComparer()).Compare(y, x);
        } //IComparer.Compare
    } //MyReverserClass

    public static void main(String[] args)
    {
        // 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);
    } //main

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

*/

Windows 98, Windows 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 .NET Framework does not support all versions of every platform. For a list of the supported versions, see System Requirements.

.NET Framework

Supported in: 2.0, 1.1, 1.0

.NET Compact Framework

Supported in: 2.0

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