Non-Generic Collection with Queue in C#

Collections in C#

C# includes varies classes that store the values or objects are called collections.

There are two types of collections available in C#:

• Non-generic collections
• Generic collections

The System.Collections namespace contains the non-generic collection types and System.Collections.Generic namespace includes generic collection types.

In most cases, it is recommended to use the generic collections because they perform faster than non-generic collections and also minimize exceptions by giving compile-time errors.

Non-generic Collections

• Arraylist
• Stack
• Queue
• Hashtable

Queue in C#

Create a Queue in C#

To create Queue<T> in C#, we need to use the System.Collection.Generic namespace.

Queue<dataType> queueName = new Queue<dataType>();

Here, dataType indicates the queue's type. For example.

// create integer type stack
Queue<int> queue1 = new Queue<int>();

// create string type stack
Queue<string> queue2 = new Queue<string>();

Example

using System;
using System.Collections.Generic;

class Program
{
    public static void Main()
    {
        // create a queue 
        Queue<string> fruits = new Queue<string>();

        // adds "Apple" and "Orange" to the queue
        fruits.Enqueue("Apple");
        fruits.Enqueue("Orange");

        // print elements of the queue 
        foreach (string item in fruits)
        {
            Console.WriteLine(item);
        }
    }
}

C# Queue Methods

C# provides 3 major Queue<T> methods. These methods are:

1. Enqueue(): using System; using System.Collections.Generic; class Program {     public static void Main()     {         // create a queue          Queue<int> numbers = new Queue<int>();         // adds 65 and 17 to the queue         numbers.Enqueue(65);         numbers.Enqueue(17);         // print elements of the queue          foreach (int item in numbers)         {             Console.WriteLine(item);         }     } }
2. Dequeue(): removes and returns an element from the beginning of the queue.

   using System;
   using System.Collections.Generic;
   
   class Program
   {
       public static void Main()
       {
           // create a queue 
           Queue<string> colors = new Queue<string>();
   
           // adds "Red" and "Blue" to the queue
           colors.Enqueue("Red");
           colors.Enqueue("Blue");
   
           // removes element from the beginning of the colors queue 
           var removedElement = colors.Dequeue();
   
           Console.WriteLine("Removed Element: " + removedElement);
       }
   }

3. Peek(): returns an element from the beginning of the queue without removing it.

   using System;
   using System.Collections.Generic;
   
   class Program
   {
       public static void Main()
       {
           // create a queue 
           Queue<string> planet = new Queue<string>();
   
           // adds "Earth" and "Jupiter" to the queue
           planet.Enqueue("Earth");
           planet.Enqueue("Jupiter");
   
           // returns element from the beginning of the planet queue
           Console.WriteLine("Element at beginning of queue: " + planet.Peek());
       }
   }
   

Happy Coding!

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