System.Collections.Generic.Queue<T>

The Queue<T> generic collection is a general-purpose collection that stores objects of the specified type.

A Queue<T> object represents a First-In, First-Out (FIFO) collection of objects. Objects can be added to the end of the queue and removed from the beginning of the queue.

When to Use a Queue

Use the Queue<T> generic collection when your application requires:

• A collection of items that must be processed in the order they were added.
• The ability to add items to the end and remove items from the beginning.

Performance Characteristics

The Queue<T> generic collection is designed for high performance. Most operations (adding and removing elements) are O(1).

Example Usage

The following example demonstrates how to declare, initialize, and populate a Queue<string>, and then process the items.

using System;
using System.Collections.Generic;

public class Example
{
    public static void Main()
    {
        // Declare and initialize a Queue of strings.
        Queue<string> queue = new Queue<string>();

        // Add elements to the queue.
        queue.Enqueue("Apple");
        queue.Enqueue("Banana");
        queue.Enqueue("Cherry");

        // Display the number of elements in the queue.
        Console.WriteLine("Count: {0}", queue.Count);

        // Dequeue and display elements.
        while (queue.Count > 0)
        {
            string fruit = queue.Dequeue();
            Console.WriteLine("Dequeued: {0}", fruit);
        }

        // Check if the queue is empty.
        if (queue.Count == 0)
        {
            Console.WriteLine("The queue is now empty.");
        }
    }
}

Methods

The Queue<T> class provides several useful methods:

Properties