ArrayList.Sort Method

Source:

ArrayList.cs

Source:

ArrayList.cs

Source:

ArrayList.cs

Source:

ArrayList.cs

Source:

ArrayList.cs

public:
 virtual void Sort();

public virtual void Sort();

abstract member Sort : unit -> unit
override this.Sort : unit -> unit

Public Overridable Sub Sort ()

Exceptions

Examples

The following code example shows how to sort the values in an ArrayList.

using System;
using System.Collections;

public class SamplesArrayList1
{
 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);

 // Sorts the values of the ArrayList.
 myAL.Sort();

 // Displays the values of the ArrayList.
 Console.WriteLine("After sorting:");
 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 sorting:
 brown
 dog
 fox
 jumps
 lazy
 over
 quick
 the
 The
*/

Imports System.Collections

Public Class SamplesArrayList

 Public Shared Sub Main()

 ' Creates and initializes a new ArrayList.
 Dim myAL As 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)

 ' Sorts the values of the ArrayList.
 myAL.Sort()

 ' Displays the values of the ArrayList.
 Console.WriteLine("After sorting:")
 PrintValues(myAL)

 End Sub

 Public Shared Sub PrintValues(myList As IEnumerable)
 Dim obj As [Object]
 For Each obj In myList
 Console.WriteLine(" {0}", obj)
 Next obj
 Console.WriteLine()
 End Sub

End Class


' This code produces the following output.
'
' The ArrayList initially contains the following values:
' The
' quick
' brown
' fox
' jumps
' over
' the
' lazy
' dog
'
' After sorting:
' brown
' dog
' fox
' jumps
' lazy
' over
' quick
' the
' The

Remarks

This method uses Array.Sort, which uses the QuickSort algorithm. The QuickSort algorithm is a comparison sort (also called an unstable sort), which means that a "less than or equal to" comparison operation determines which of two elements should occur first in the final sorted list. However, if two elements are equal, their original 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 to use with the other overloads of this method.

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.

See also

• Performing Culture-Insensitive String Operations in Collections

Source:

ArrayList.cs

Source:

ArrayList.cs

Source:

ArrayList.cs

Source:

ArrayList.cs

Source:

ArrayList.cs

public:
 virtual void Sort(System::Collections::IComparer ^ comparer);

public virtual void Sort(System.Collections.IComparer comparer);

public virtual void Sort(System.Collections.IComparer? comparer);

abstract member Sort : System.Collections.IComparer -> unit
override this.Sort : System.Collections.IComparer -> unit

Public Overridable Sub Sort (comparer As IComparer)

Parameters

Exceptions

Examples

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

using System;
using System.Collections;

public class SamplesArrayList2
{
 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("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:");
 PrintIndexAndValues(myAL);

 // Sorts the values of the ArrayList using the default comparer.
 myAL.Sort();
 Console.WriteLine("After sorting with the default comparer:");
 PrintIndexAndValues(myAL);

 // Sorts the values of the ArrayList using the reverse case-insensitive comparer.
 IComparer myComparer = new myReverserClass();
 myAL.Sort(myComparer);
 Console.WriteLine("After sorting 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]: jumps
 [5]: over
 [6]: the
 [7]: lazy
 [8]: dog

After sorting with the default comparer:
 [0]: brown
 [1]: dog
 [2]: fox
 [3]: jumps
 [4]: lazy
 [5]: over
 [6]: quick
 [7]: the
 [8]: The

After sorting with the reverse case-insensitive comparer:
 [0]: the
 [1]: The
 [2]: quick
 [3]: over
 [4]: lazy
 [5]: jumps
 [6]: fox
 [7]: dog
 [8]: brown
*/

Imports System.Collections

Public Class SamplesArrayList

 Public Class myReverserClass
 Implements IComparer

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

 End Class

 Public Shared Sub Main()

 ' Creates and initializes a new ArrayList.
 Dim myAL As 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:")
 PrintIndexAndValues(myAL)

 ' Sorts the values of the ArrayList using the default comparer.
 myAL.Sort()
 Console.WriteLine("After sorting with the default comparer:")
 PrintIndexAndValues(myAL)

 ' Sorts the values of the ArrayList using the reverse case-insensitive comparer.
 Dim myComparer = New myReverserClass()
 myAL.Sort(myComparer)
 Console.WriteLine("After sorting with the reverse case-insensitive comparer:")
 PrintIndexAndValues(myAL)

 End Sub

 Public Shared Sub PrintIndexAndValues(myList As IEnumerable)
 Dim i As Integer = 0
 Dim obj As [Object]
 For Each obj In myList
 Console.WriteLine(vbTab + "[{0}]:" + vbTab + "{1}", i, obj)
 i = i + 1
 Next obj
 Console.WriteLine()
 End Sub

End Class


'This code produces the following output.
'The ArrayList initially contains the following values:
' [0]: The
' [1]: quick
' [2]: brown
' [3]: fox
' [4]: jumps
' [5]: over
' [6]: the
' [7]: lazy
' [8]: dog
'
'After sorting with the default comparer:
' [0]: brown
' [1]: dog
' [2]: fox
' [3]: jumps
' [4]: lazy
' [5]: over
' [6]: quick
' [7]: the
' [8]: The
'
'After sorting with the reverse case-insensitive comparer:
' [0]: the
' [1]: The
' [2]: quick
' [3]: over
' [4]: lazy
' [5]: jumps
' [6]: fox
' [7]: dog
' [8]: brown

Remarks

Use the Sort method to sort a list of objects with a custom comparer that implements the IComparer interface. If you pass null for comparer, this method uses the IComparable implementation of each element. In this case, you must make sure that the objects contained in the list implement the IComparer interface or an exception will occur.

In addition, using the IComparable implementation means the list 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.

See also

• Performing Culture-Insensitive String Operations in Collections

Source:

ArrayList.cs

Source:

ArrayList.cs

Source:

ArrayList.cs

Source:

ArrayList.cs

Source:

ArrayList.cs

public:
 virtual void Sort(int index, int count, System::Collections::IComparer ^ comparer);

public virtual void Sort(int index, int count, System.Collections.IComparer comparer);

public virtual void Sort(int index, int count, System.Collections.IComparer? comparer);

abstract member Sort : int * int * System.Collections.IComparer -> unit
override this.Sort : int * int * System.Collections.IComparer -> unit

Public Overridable Sub Sort (index As Integer, count As Integer, comparer As IComparer)

Parameters

Exceptions

Examples

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 SamplesArrayList3
{
 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("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:");
 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]: jumps
 [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]: jumps
 [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]: jumps
 [5]: over
 [6]: the
 [7]: lazy
 [8]: dog
*/

Imports System.Collections

Public Class SamplesArrayList

 Public Class myReverserClass
 Implements IComparer

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

 End Class

 Public Shared Sub Main()

 ' Creates and initializes a new ArrayList.
 Dim myAL As 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:")
 PrintIndexAndValues(myAL)

 ' Sorts the values of the ArrayList using the default comparer.
 myAL.Sort(1, 3, Nothing)
 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.
 Dim 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)

 End Sub

 Public Shared Sub PrintIndexAndValues(myList As IEnumerable)
 Dim i As Integer = 0
 Dim obj As [Object]
 For Each obj In myList
 Console.WriteLine(vbTab + "[{0}]:" + vbTab + "{1}", i, obj)
 i = i + 1
 Next obj
 Console.WriteLine()
 End Sub

End Class


'This code produces the following output.
'The ArrayList initially contains the following values:
' [0]: The
' [1]: QUICK
' [2]: BROWN
' [3]: FOX
' [4]: jumps
' [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]: jumps
' [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]: jumps
' [5]: over
' [6]: the
' [7]: lazy
' [8]: dog

Remarks

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.

See also

• Performing Culture-Insensitive String Operations in Collections