How to create a queue from an existing collection in C#
The Queue<T> generic class in the System.Collections.Generic namespace provides the Queue<T>(IEnumerable<T>) constructor, which is used to create a new instance of Queue<T> with elements copied from the specified Collection of elements.
Syntax
public Queue (System.Collections.Generic.IEnumerable<T> collection);
This constructor takes an IEnumerable<T> as input, and copies the elements for the specified collection to create a new instance of Queue.
Things to note
- This method throws an exception if the input collection is null.
- This is an O(n) operation, where n is the number of elements in the specified collection.
- The
Queue<T>instance created with this constructor has elements in the same order as present in theIEnumerator<T>of the specified collection.
In this example, we first declare and initialize an array of strings with names of months and print the contents of the array.
Next, we create a new instance of Queue<string>; we pass the array of strings in the Queue constructor parameter.
Queue<string> monthQueue = new Queue<string>(monthsArray);
We demonstrate how this constructor functions with an example of a List of strings as well.
using System;using System.Collections.Generic;class QueueConstructor{static void Main(){string[] monthsArray = {"January", "Feburary", "March", "April"};Console.WriteLine("Array Elements: {0}", string.Join(",", monthsArray));Queue<string> monthQueue = new Queue<string>(monthsArray);Console.WriteLine("Enqueued all array Elements to the Queue \nQueue Items : {0}", string.Join(",", monthQueue.ToArray()));List<string> animals = new List<string>{"dog","cat", "lion", "zebra"};Console.WriteLine("List Elements: {0}", string.Join(",", animals.ToArray()));Queue<string> animalQueue = new Queue<string>(animals);Console.WriteLine("Enqueued all List Elements to the Queue \nQueue Items : {0}", string.Join(",", animalQueue.ToArray()));}}
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