Queue.GetEnumerator Method in C#

This method returns an enumerator that iterates through the Queue. And it comes under the System.Collections namespace.

Syntax:

public virtual System.Collections.IEnumerator GetEnumerator ();

Below programs illustrate the use of above-discussed method:

Example 1:

// C# code to illustrate the
// Queue.GetEnumerator Method
using System;
using System.Collections;

class GFG {

    // Driver code
    public static void Main()
    {

        // Creating an Queue
        Queue myq = new Queue();

        // Adding elements to Queue
        myq.Enqueue("A");
        myq.Enqueue("B");
        myq.Enqueue("C");
        myq.Enqueue("D");
        myq.Enqueue("E");
        myq.Enqueue("F");

        // To get an Enumerator
        // for the Queue
        IEnumerator enumerator = myq.GetEnumerator();

        // If MoveNext passes the end of the
        // collection, the enumerator is positioned
        // after the last element in the Queue
        // and MoveNext returns false.
        while (enumerator.MoveNext())
        {

            Console.WriteLine(enumerator.Current);
        }
    }
}

Output:

A
B
C
D
E
F

Example 2:

// C# code to illustrate the
// Queue.GetEnumerator Method
using System;
using System.Collections;

class GFG {

    // Driver code
    public static void Main()
    {

        // Creating an Queue
        Queue myq = new Queue();

        // Adding elements to Queue
        myq.Enqueue(78);
        myq.Enqueue(84);
        myq.Enqueue(44);
        myq.Enqueue(77);
        myq.Enqueue(99);

        // To get an Enumerator
        // for the Queue
        IEnumerator enumerator = myq.GetEnumerator();

        // If MoveNext passes the end of the
        // collection, the enumerator is positioned
        // after the last element in the Queue
        // and MoveNext returns false.
        while (enumerator.MoveNext()) {

            Console.WriteLine(enumerator.Current);
        }
    }
}

Output:

78
84
44
77
99

Note:

• The foreach statement of the C# language hides the complexity of the enumerators. Therefore, using foreach is recommended, instead of directly manipulating the enumerator.
• Enumerators can be used to read the data in the collection, but they cannot be used to modify the underlying collection.
• Current returns the same object until either MoveNext or Reset is called. MoveNext sets Current to the next element.
• An enumerator remains valid as long as the collection remains unchanged. If changes are made to the collection, such as adding, modifying, or deleting elements, the enumerator is irrecoverably invalidated and its behavior is undefined.
• This method is an O(1) operation.

Reference:

• https://docs.microsoft.com/en-us/dotnet/api/system.collections.queue.getenumerator?view=netframework-4.7.2