Queue<T> Constructeurs

Définition

Surcharges

Exemples

L’exemple de code suivant illustre ce constructeur et plusieurs autres méthodes de la Queue<T> classe générique. L’exemple de code crée une file d’attente de chaînes avec une capacité par défaut et utilise la Enqueue méthode pour mettre en file d’attente cinq chaînes. Les éléments de la file d’attente sont énumérés, ce qui ne modifie pas l’état de la file d’attente. La Dequeue méthode est utilisée pour mettre la première chaîne en file d’attente. La Peek méthode est utilisée pour examiner l’élément suivant dans la file d’attente, puis la Dequeue méthode est utilisée pour le mettre en file d’attente.

La ToArray méthode est utilisée pour créer un tableau et y copier les éléments de file d’attente, puis le tableau est passé au Queue<T> constructeur qui prend IEnumerable<T>, en créant une copie de la file d’attente. Les éléments de la copie sont affichés.

Un tableau double de la taille de la file d’attente est créé, et la CopyTo méthode est utilisée pour copier les éléments du tableau en commençant au milieu du tableau. Le Queue<T> constructeur est utilisé à nouveau pour créer une deuxième copie de la file d’attente contenant trois éléments Null au début.

La Contains méthode est utilisée pour montrer que la chaîne « four » se trouve dans la première copie de la file d’attente, après quoi la Clear méthode efface la copie et la Count propriété indique que la file d’attente est vide.

using System;
using System.Collections.Generic;

class Example
{
    public static void Main()
    {
        Queue<string> numbers = new Queue<string>();
        numbers.Enqueue("one");
        numbers.Enqueue("two");
        numbers.Enqueue("three");
        numbers.Enqueue("four");
        numbers.Enqueue("five");

        // A queue can be enumerated without disturbing its contents.
        foreach( string number in numbers )
        {
            Console.WriteLine(number);
        }

        Console.WriteLine("\nDequeuing '{0}'", numbers.Dequeue());
        Console.WriteLine("Peek at next item to dequeue: {0}",
            numbers.Peek());
        Console.WriteLine("Dequeuing '{0}'", numbers.Dequeue());

        // Create a copy of the queue, using the ToArray method and the
        // constructor that accepts an IEnumerable<T>.
        Queue<string> queueCopy = new Queue<string>(numbers.ToArray());

        Console.WriteLine("\nContents of the first copy:");
        foreach( string number in queueCopy )
        {
            Console.WriteLine(number);
        }

        // Create an array twice the size of the queue and copy the
        // elements of the queue, starting at the middle of the
        // array.
        string[] array2 = new string[numbers.Count * 2];
        numbers.CopyTo(array2, numbers.Count);

        // Create a second queue, using the constructor that accepts an
        // IEnumerable(Of T).
        Queue<string> queueCopy2 = new Queue<string>(array2);

        Console.WriteLine("\nContents of the second copy, with duplicates and nulls:");
        foreach( string number in queueCopy2 )
        {
            Console.WriteLine(number);
        }

        Console.WriteLine("\nqueueCopy.Contains(\"four\") = {0}",
            queueCopy.Contains("four"));

        Console.WriteLine("\nqueueCopy.Clear()");
        queueCopy.Clear();
        Console.WriteLine("\nqueueCopy.Count = {0}", queueCopy.Count);
    }
}

/* This code example produces the following output:

one
two
three
four
five

Dequeuing 'one'
Peek at next item to dequeue: two
Dequeuing 'two'

Contents of the first copy:
three
four
five

Contents of the second copy, with duplicates and nulls:



three
four
five

queueCopy.Contains("four") = True

queueCopy.Clear()

queueCopy.Count = 0
 */

open System
open System.Collections.Generic

let numbers = Queue()
numbers.Enqueue "one"
numbers.Enqueue "two"
numbers.Enqueue "three"
numbers.Enqueue "four"
numbers.Enqueue "five"

// A queue can be enumerated without disturbing its contents.
for number in numbers do
    printfn $"{number}"

printfn $"\nDequeuing '{numbers.Dequeue()}'"
printfn $"Peek at next item to dequeue: {numbers.Peek()}"
printfn $"Dequeuing '{numbers.Dequeue()}'"

// Create a copy of the queue, using the ToArray method and the
// constructor that accepts an IEnumerable<T>.
let queueCopy = numbers.ToArray() |> Queue

printfn $"\nContents of the first copy:"
for number in queueCopy do
    printfn $"{number}"

// Create an array twice the size of the queue and copy the
// elements of the queue, starting at the middle of the
// array.
let array2 = numbers.Count * 2 |> Array.zeroCreate
numbers.CopyTo(array2, numbers.Count)

// Create a second queue, using the constructor that accepts an
// IEnumerable(Of T).
let queueCopy2 = Queue array2

printfn $"\nContents of the second copy, with duplicates and nulls:"
for number in queueCopy2 do
    printfn $"{number}"
printfn $"""\nqueueCopy.Contains "four" = {queueCopy.Contains "four"}"""

printfn $"\nqueueCopy.Clear()"
queueCopy.Clear()
printfn $"queueCopy.Count = {queueCopy.Count}"

// This code example produces the following output:
//       one
//       two
//       three
//       four
//       five
//       
//       Dequeuing 'one'
//       Peek at next item to dequeue: two
//       Dequeuing 'two'
//       
//       Contents of the first copy:
//       three
//       four
//       five
//       
//       Contents of the second copy, with duplicates and nulls:
//       
//       
//       
//       three
//       four
//       five
//       
//       queueCopy.Contains "four" = True
//       
//       queueCopy.Clear()
//       
//       queueCopy.Count = 0

Imports System.Collections.Generic

Module Example

    Sub Main

        Dim numbers As New Queue(Of String)
        numbers.Enqueue("one")
        numbers.Enqueue("two")
        numbers.Enqueue("three")
        numbers.Enqueue("four")
        numbers.Enqueue("five")

        ' A queue can be enumerated without disturbing its contents.
        For Each number As String In numbers
            Console.WriteLine(number)
        Next

        Console.WriteLine(vbLf & "Dequeuing '{0}'", numbers.Dequeue())
        Console.WriteLine("Peek at next item to dequeue: {0}", _
            numbers.Peek())    
        Console.WriteLine("Dequeuing '{0}'", numbers.Dequeue())

        ' Create a copy of the queue, using the ToArray method and the
        ' constructor that accepts an IEnumerable(Of T).
        Dim queueCopy As New Queue(Of String)(numbers.ToArray())

        Console.WriteLine(vbLf & "Contents of the first copy:")
        For Each number As String In queueCopy
            Console.WriteLine(number)
        Next
        
        ' Create an array twice the size of the queue, compensating
        ' for the fact that Visual Basic allocates an extra array 
        ' element. Copy the elements of the queue, starting at the
        ' middle of the array. 
        Dim array2((numbers.Count * 2) - 1) As String
        numbers.CopyTo(array2, numbers.Count)
        
        ' Create a second queue, using the constructor that accepts an
        ' IEnumerable(Of T).
        Dim queueCopy2 As New Queue(Of String)(array2)

        Console.WriteLine(vbLf & _
            "Contents of the second copy, with duplicates and nulls:")
        For Each number As String In queueCopy2
            Console.WriteLine(number)
        Next

        Console.WriteLine(vbLf & "queueCopy.Contains(""four"") = {0}", _
            queueCopy.Contains("four"))

        Console.WriteLine(vbLf & "queueCopy.Clear()")
        queueCopy.Clear()
        Console.WriteLine(vbLf & "queueCopy.Count = {0}", _
            queueCopy.Count)
    End Sub
End Module

' This code example produces the following output:
'
'one
'two
'three
'four
'five
'
'Dequeuing 'one'
'Peek at next item to dequeue: two
'
'Dequeuing 'two'
'
'Contents of the copy:
'three
'four
'five
'
'Contents of the second copy, with duplicates and nulls:
'
'
'
'three
'four
'five
'
'queueCopy.Contains("four") = True
'
'queueCopy.Clear()
'
'queueCopy.Count = 0

public:
 Queue();

public Queue ();

Public Sub New ()

public:
 Queue(System::Collections::Generic::IEnumerable<T> ^ collection);

public Queue (System.Collections.Generic.IEnumerable<T> collection);

new System.Collections.Generic.Queue<'T> : seq<'T> -> System.Collections.Generic.Queue<'T>

Public Sub New (collection As IEnumerable(Of T))

public:
 Queue(int capacity);

public Queue (int capacity);

new System.Collections.Generic.Queue<'T> : int -> System.Collections.Generic.Queue<'T>

Public Sub New (capacity As Integer)