C# | Getting an enumerator for the entire ArrayList

ArrayList.GetEnumerator Method is used to get an enumerator for the entire ArrayList.

Syntax:

public virtual System.Collections.IEnumerator GetEnumerator ();

Return Value: It returns an IEnumerator for the entire ArrayList.

Below programs illustrate the use of above-discussed method:

Example 1:

// C# code to get an enumerator
// for the entire ArrayList
using System;
using System.Collections;

class GFG {

    // Driver code
    public static void Main()
    {

        // Creating an ArrayList
        ArrayList myList = new ArrayList();

        // adding elements in myList
        myList.Add("Geeks");
        myList.Add("GFG");
        myList.Add("C#");
        myList.Add("Tutorials");

        // To get an Enumerator
        // for the ArrayList
        IEnumerator enumerator = myList.GetEnumerator();

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

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

Output:

Geeks
GFG
C#
Tutorials

Example 2:

// C# code to get an enumerator
// for the entire ArrayList
using System;
using System.Collections;

class GFG {

    // Driver code
    public static void Main()
    {

        // Creating an ArrayList
        ArrayList myList = new ArrayList();

        // adding elements in myList
        myList.Add(14);
        myList.Add(45);
        myList.Add(78);
        myList.Add(57);

        // To get an Enumerator
        // for the ArrayList
        IEnumerator enumerator = myList.GetEnumerator();

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

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

Output:

14
45
78
57

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.arraylist.getenumerator?view=netframework-4.7.2