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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)

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-

Nothing to sort only the keys Array.

comparer
Type: System.Collections.IComparer

The IComparer implementation to use when comparing elements.

-or-

Nothing to use the IComparable implementation of each element.

ExceptionCondition
ArgumentNullException

keys is Nothing.

RankException

The keys Array is multidimensional.

-or-

The items Array is multidimensional.

ArgumentException

items is not Nothing, and the lower bound of keys does not match the lower bound of items.

-or-

items is not Nothing, 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 Nothing, 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 Nothing, 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.

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

Windows 7, Windows Vista, Windows XP SP2, Windows XP Media Center Edition, Windows XP Professional x64 Edition, Windows XP Starter Edition, Windows Server 2008 R2, Windows Server 2008, Windows Server 2003, Windows Server 2000 SP4, Windows Millennium Edition, Windows 98, Windows CE, Windows Mobile for Smartphone, Windows Mobile for Pocket PC, Xbox 360, Zune

The .NET Framework and .NET Compact Framework do not support all versions of every platform. For a list of the supported versions, see .NET Framework System Requirements.

.NET Framework

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

.NET Compact Framework

Supported in: 3.5, 2.0

XNA Framework

Supported in: 3.0, 2.0, 1.0

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