ArrayList.Sort Method (System.Collections) (original) (raw)
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Sorts the elements in a range of elements in ArrayList using the specified 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);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 -> unitPublic Overridable Sub Sort (index As Integer, count As Integer, comparer As IComparer)Parameters
index
The zero-based starting index of the range to sort.
count
The length of the range to sort.
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.
Exceptions
index is less than zero.
-or-
count is less than zero.
index and count do not specify a valid range in the ArrayList.
An error occurred while comparing two elements.
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.