List<T>.Reverse Method

Definition

Namespace:

System.Collections.Generic

Assembly:

System.Collections.dll

Reverses the order of the elements in the List<T> or a portion of it.

Overloads

Reverse()	Reverses the order of the elements in the entire List<T>.
Reverse(Int32, Int32)	Reverses the order of the elements in the specified range.

Examples

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 namespace System;
using namespace System::Collections::Generic;

void main()
{
    List<String^>^ dinosaurs = gcnew List<String^>();

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

    Console::WriteLine();
    for each(String^ dinosaur in dinosaurs)
    {
        Console::WriteLine(dinosaur);
    }

    dinosaurs->Reverse();

    Console::WriteLine();
    for each(String^ dinosaur in dinosaurs)
    {
        Console::WriteLine(dinosaur);
    }

    dinosaurs->Reverse(1, 4);

    Console::WriteLine();
    for each(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
 */

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
 */

Imports System.Collections.Generic

Public Class Example

    Public Shared Sub Main()

        Dim dinosaurs As New List(Of String)

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

        Console.WriteLine()
        For Each dinosaur As String In dinosaurs
            Console.WriteLine(dinosaur)
        Next

        dinosaurs.Reverse()

        Console.WriteLine()
        For Each dinosaur As String In dinosaurs
            Console.WriteLine(dinosaur)
        Next

        dinosaurs.Reverse(1, 4)

        Console.WriteLine()
        For Each dinosaur As String In dinosaurs
            Console.WriteLine(dinosaur)
        Next

    End Sub
End Class

' 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

Reverse()

Source:

List.cs

Reverses the order of the elements in the entire List<T>.

public:
 void Reverse();

public void Reverse ();

member this.Reverse : unit -> unit

Public Sub Reverse ()

Remarks

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

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

Reverse(Int32, Int32)

Source:

List.cs

Reverses the order of the elements in the specified range.

public:
 void Reverse(int index, int count);

public void Reverse (int index, int count);

member this.Reverse : int * int -> unit

Public Sub Reverse (index As Integer, count As Integer)

Parameters

index

Int32

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

count

Int32

The number of elements in the range to reverse.

Exceptions

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>.

Remarks

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

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