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List<T>.Reverse Method (Int32, Int32)

Reverses the order of the elements in the specified range.

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

public void Reverse(
	int index,
	int count
)

Parameters

index
Type: System.Int32

The zero-based starting index of the range to reverse.

count
Type: System.Int32

The number of elements in the range to reverse.

ExceptionCondition
ArgumentOutOfRangeException

index is less than 0.

-or-

count is less than 0.

ArgumentException

index and count do not denote a valid range of elements in the List<T>.

This method uses Array.Reverse to reverse the order of the elements.

This method is an O(n) operation, where n is Count.

The following example demonstrates both overloads of the Reverse method. The example creates a List<T> of strings and adds six strings. The Reverse() method overload is used to reverse the list, and then the Reverse(Int32, Int32) method overload is used to reverse the middle of the list, beginning with element 1 and encompassing four elements.

using System;
using System.Collections.Generic;

public class Example
{
    public static void Main()
    {
        List<string> dinosaurs = new List<string>();

        dinosaurs.Add("Pachycephalosaurus");
        dinosaurs.Add("Parasauralophus");
        dinosaurs.Add("Mamenchisaurus");
        dinosaurs.Add("Amargasaurus");
        dinosaurs.Add("Coelophysis");
        dinosaurs.Add("Oviraptor");

        Console.WriteLine();
        foreach(string dinosaur in dinosaurs)
        {
            Console.WriteLine(dinosaur);
        }

        dinosaurs.Reverse();

        Console.WriteLine();
        foreach(string dinosaur in dinosaurs)
        {
            Console.WriteLine(dinosaur);
        }

        dinosaurs.Reverse(1, 4);

        Console.WriteLine();
        foreach(string dinosaur in dinosaurs)
        {
            Console.WriteLine(dinosaur);
        }
    }
}

/* This code example produces the following output:

Pachycephalosaurus
Parasauralophus
Mamenchisaurus
Amargasaurus
Coelophysis
Oviraptor

Oviraptor
Coelophysis
Amargasaurus
Mamenchisaurus
Parasauralophus
Pachycephalosaurus

Oviraptor
Parasauralophus
Mamenchisaurus
Amargasaurus
Coelophysis
Pachycephalosaurus
 */

.NET Framework

Supported in: 4.5.2, 4.5.1, 4.5, 4, 3.5, 3.0, 2.0

.NET Framework Client Profile

Supported in: 4, 3.5 SP1

Portable Class Library

Supported in: Portable Class Library

.NET for Windows Store apps

Supported in: Windows 8

.NET for Windows Phone apps

Supported in: Windows Phone 8.1, Windows Phone 8, Silverlight 8.1

Windows Phone 8.1, Windows Phone 8, Windows 8.1, Windows Server 2012 R2, Windows 8, Windows Server 2012, Windows 7, Windows Vista SP2, Windows Server 2008 (Server Core Role not supported), Windows Server 2008 R2 (Server Core Role supported with SP1 or later; Itanium not supported)

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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