C# | Get an enumerator that iterates through the SortedList

SortedList.GetEnumerator Method is used to an IDictionaryEnumerator object that iterates through a SortedList object.

Syntax:

public virtual System.Collections.IDictionaryEnumerator GetEnumerator ();

Return Value: This method returns an IDictionaryEnumerator object for the SortedList object.

Below programs illustrate the use of above discussed method:

Example 1:

// C# code to get IDictionaryEnumerator object
// that iterates through a SortedList object
using System;
using System.Collections;

class Geeks {

    // Main Method
    public static void Main(String[] args)
    {

        // Creating a SortedList of integers
        SortedList mylist = new SortedList();

        // Adding elements to SortedList
        mylist.Add("1", "C++");
        mylist.Add("2", "Java");
        mylist.Add("3", "DSA");
        mylist.Add("4", "Python");
        mylist.Add("5", "C#");

        // To get an IDictionaryEnumerator
        // for the SortedList
        IDictionaryEnumerator myEnumerator =
                             mylist.GetEnumerator();

        // If MoveNext passes the end of the
        // collection, the enumerator is positioned
        // after the last element in the collection
        // and MoveNext returns false.
        while (myEnumerator.MoveNext())
            Console.WriteLine(myEnumerator.Key + " --> "
                              + myEnumerator.Value);
    }
}

Output:

1 --> C++
2 --> Java
3 --> DSA
4 --> Python
5 --> C#

Example 2:

// C# code to get IDictionaryEnumerator object
// that iterates through a SortedList object
using System;
using System.Collections;

class Geeks {

    // Main Method
    public static void Main(String[] args)
    {

        // Creating a SortedList of integers
        SortedList mylist = new SortedList();

        // Adding elements to SortedList
        mylist.Add("Australia", "Canberra");
        mylist.Add("Belgium", "Brussels");
        mylist.Add("Netherlands", "Amsterdam");
        mylist.Add("China", "Beijing");
        mylist.Add("Russia", "Moscow");
        mylist.Add("India", "New Delhi");

        // To get an IDictionaryEnumerator
        // for the SortedList
        IDictionaryEnumerator myEnumerator =
                             mylist.GetEnumerator();

        // If MoveNext passes the end of the
        // collection, the enumerator is positioned
        // after the last element in the collection
        // and MoveNext returns false.
        while (myEnumerator.MoveNext())
            Console.WriteLine(myEnumerator.Key + " --> "
                              + myEnumerator.Value);
    }
}

Output:

Australia --> Canberra
Belgium --> Brussels
China --> Beijing
India --> New Delhi
Netherlands --> Amsterdam
Russia --> Moscow

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.sortedlist.getenumerator?view=netframework-4.7.2