C# | Get an enumerator that iterates through the stringDictionary

StringDictionary.GetEnumerator method is used to return an enumerator that iterates through the string dictionary.

Syntax:

public virtual System.Collections.IEnumerator GetEnumerator ();

Return Value: An IEnumerator that iterates through the string dictionary.

Below given are some examples to understand the implementation in a better way:

Example 1:

// C# code to get an enumerator
// that iterates through the stringDictionary
using System;
using System.Collections;
using System.Collections.Specialized;

class GFG {

    // Driver code
    public static void Main()
    {

        // Creating a StringDictionary named myDict
        StringDictionary myDict = new StringDictionary();

        // Adding key and value into the StringDictionary
        myDict.Add("A", "Apple");
        myDict.Add("B", "Banana");
        myDict.Add("C", "Cat");
        myDict.Add("D", "Dog");

        // "IEnumerator" interface supports a simple
        // iteration over a non-generic collection.
        IEnumerator myEnumerator = myDict.GetEnumerator();

        DictionaryEntry de;

        // "MoveNext" advances the enumerator
        // to the next element of the collection.
        // you must call "MoveNext" to advance the
        // enumerator to the first element of the
        // collection before reading the value of "Current"
        while (myEnumerator.MoveNext()) {

            // "Current" returns the same object until
            // either "MoveNext" is called.
            // "MoveNext" sets "Current" to the next element.
            de = (DictionaryEntry)myEnumerator.Current;
            Console.WriteLine(de.Key + " " + de.Value);
        }
    }
}

Output:

d Dog
b Banana
c Cat
a Apple

Example 2:

// C# code to get an enumerator
// that iterates through the stringDictionary
using System;
using System.Collections;
using System.Collections.Specialized;

class GFG {

    // Driver code
    public static void Main()
    {

        // Creating a StringDictionary named myDict
        StringDictionary myDict = new StringDictionary();

        // Adding key and value into the StringDictionary
        myDict.Add("I", "one");
        myDict.Add("II", "two");
        myDict.Add("III", "three");
        myDict.Add("IV", "four");
        myDict.Add("V", "five");

        // "IEnumerator" interface supports a simple
        // iteration over a non-generic collection.
        IEnumerator myEnumerator = myDict.GetEnumerator();

        DictionaryEntry de;

        // "MoveNext" advances the enumerator
        // to the next element of the collection.
        // you must call "MoveNext" to advance the
        // enumerator to the first element of the
        // collection before reading the value of "Current"
        while (myEnumerator.MoveNext()) {

            // "Current" returns the same object until
            // either "MoveNext" is called.
            // "MoveNext" sets "Current" to the next element.
            de = (DictionaryEntry)myEnumerator.Current;
            Console.WriteLine(de.Key + " " + de.Value);
        }
    }
}

Output:

iv four
i one
iii three
v five
ii two

Note:

• Enumerators can be used to read the data in the collection, but they cannot be used to modify the underlying collection.
• 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.specialized.stringdictionary.getenumerator?view=netframework-4.7.2