Queue in C#

In this article, we will learn about the queue class in C#.

A queue represents a variable size first-in-first-out (FIFO) collection of instances of the same specified type.

Three main operations can be performed on a Queue and its elements: <ul><li>Enqueue adds an element to the end of the Queue.</li> <li>Dequeue removes the oldest element from the start of the Queue.</li> <li>Peek returns the oldest element that is at the start of the Queue but does not remove it from the Queue.<li> </ul> <h4>Creating a Queue</h4> <p>We create a Queue in C# using the following syntax:
Queue<T> q = new Queue<T>();
<T> here denotes any datatype which we want to create a stack of.

Properties of Queue

• Count: This property gets the number of elements present in the stack.

Methods of Stack

• Enqueue(T): Adds an object to the end of the Queue.</li>
• Dequeue(): Removes and returns the object at the beginning of the Queue.</li>
• Peek(): Returns the object at the beginning of the Queue without removing it.</li>
• Contains(T): Determines whether an element is in the Queue.</li>
• Clear(): Removes all objects from the Queue.</li> </ul>

  ---

  Queue Operation Examples:

  Different Queue operations are demonstrated in the example below:

  using System;
  using System.Collections.Generic;
  namespace QueueDemo {
      class Example {
          static void Main(string[] args) {
              Queue  q = new Queue ();
              q.Enqueue(5);          
              q.Enqueue(5);
              q.Enqueue(2);
              q.Enqueue(9);
              
              Console.WriteLine(q.Count);        // Prints 4, the size of queue
              
              Console.WriteLine(q.Peek());       // Prints 5, the oldest element
              
              Console.WriteLine(q.Dequeue());       // Prints 5, then removes it
              Console.WriteLine(q.Dequeue());       // Prints 5, then removes it
              
              Console.WriteLine(st.Contains(5));  // Checks if 5 is present
              Console.WriteLine(st.Contains(2));  // Checks if 2 is present
          }
      }
  }
  </code></pre>
  Output: 
  4
  
  5
  
  5
  
  5
  
  False
  
  True
  
  
  Task
  In the editor below, perform the different tasks as directed.