Queue<T>.Count プロパティ

定義

Queue<T> に格納されている要素の数を取得します。Gets the number of elements contained in the Queue<T>.

public:
 property int Count { int get(); };
public int Count { get; }
member this.Count : int
Public ReadOnly Property Count As Integer

プロパティ値

Int32

Queue<T> に格納されている要素の数。The number of elements contained in the Queue<T>.

実装

次のコード例は、Count プロパティを含む Queue<T> ジェネリッククラスのいくつかのプロパティとメソッドを示しています。The following code example demonstrates several properties and methods of the Queue<T> generic class, including the Count property.

このコード例では、既定の容量を使用して文字列のキューを作成し、Enqueue メソッドを使用して5つの文字列をキューに置いています。The code example creates a queue of strings with default capacity and uses the Enqueue method to queue five strings. キューの要素が列挙され、キューの状態が変更されることはありません。The elements of the queue are enumerated, which does not change the state of the queue. Dequeue メソッドは、最初の文字列をデキューするために使用されます。The Dequeue method is used to dequeue the first string. Peek メソッドは、キュー内の次の項目を確認するために使用されます。その後、Dequeue メソッドを使用してキューからデキューされます。The Peek method is used to look at the next item in the queue, and then the Dequeue method is used to dequeue it.

ToArray メソッドを使用して配列を作成し、その配列に queue 要素をコピーします。その後、IEnumerable<T>を受け取る Queue<T> コンストラクターに配列が渡され、キューのコピーが作成されます。The ToArray method is used to create an array and copy the queue elements to it, then the array is passed to the Queue<T> constructor that takes IEnumerable<T>, creating a copy of the queue. コピーの要素が表示されます。The elements of the copy are displayed.

キューのサイズの2倍の配列が作成され、CopyTo メソッドを使用して配列の途中から配列の要素がコピーされます。An array twice the size of the queue is created, and the CopyTo method is used to copy the array elements beginning at the middle of the array. Queue<T> コンストラクターは、最初に3つの null 要素を含むキューの2番目のコピーを作成するために使用されます。The Queue<T> constructor is used again to create a second copy of the queue containing three null elements at the beginning.

Contains メソッドは、文字列 "4" がキューの最初のコピーに含まれていることを示すために使用されます。その後、Clear メソッドによってコピーがクリアされ、Count プロパティによってキューが空であることが示されます。The Contains method is used to show that the string "four" is in the first copy of the queue, after which the Clear method clears the copy and the Count property shows that the queue is empty.

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 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

注釈

Queue<T> の容量は、Queue<T> が格納できる要素の数です。The capacity of a Queue<T> is the number of elements that the Queue<T> can store. Count は、実際に Queue<T>内にある要素の数です。Count is the number of elements that are actually in the Queue<T>.

容量は常に Count 以上です。The capacity is always greater than or equal to Count. 要素を追加するときに Count が容量を上回る場合、容量は、古い要素をコピーして新しい要素を追加する前に、内部配列を自動的に再割り当てすることによって増加します。If Count exceeds the capacity while adding elements, the capacity is increased by automatically reallocating the internal array before copying the old elements and adding the new elements.

このプロパティ値を取得することは、O(1) 操作になります。Retrieving the value of this property is an O(1) operation.

適用対象