Get an enumerator that iterates through the StringDictionary in C#

The StringDictionary class in C# provides the GetEnumerator() method to obtain an enumerator that iterates through the collection. This enumerator returns DictionaryEntry objects containing key-value pairs. Note that StringDictionary automatically converts all keys to lowercase during storage.

Syntax

Following is the syntax for getting an enumerator from StringDictionary −

IEnumerator enumerator = stringDictionary.GetEnumerator();

To iterate through the enumerator −

while (enumerator.MoveNext()) {
    DictionaryEntry entry = (DictionaryEntry)enumerator.Current;
    // Use entry.Key and entry.Value
}

Using GetEnumerator() Method

The following example demonstrates how to use GetEnumerator() to iterate through a StringDictionary −

using System;
using System.Collections;
using System.Collections.Specialized;

public class Demo {
    public static void Main() {
        StringDictionary strDict1 = new StringDictionary();
        strDict1.Add("A", "John");
        strDict1.Add("B", "Andy");
        strDict1.Add("C", "Tim");
        strDict1.Add("D", "Ryan");
        strDict1.Add("E", "Kevin");
        strDict1.Add("F", "Katie");
        strDict1.Add("G", "Brad");
        
        Console.WriteLine("StringDictionary1 elements...");
        foreach(DictionaryEntry de in strDict1) {
            Console.WriteLine(de.Key + " " + de.Value);
        }
        
        StringDictionary strDict2 = new StringDictionary();
        strDict2.Add("1", "A");
        strDict2.Add("2", "B");
        strDict2.Add("3", "C");
        strDict2.Add("4", "D");
        strDict2.Add("5", "E");
        
        Console.WriteLine("\nStringDictionary2 key-value pairs...");
        IEnumerator demoEnum = strDict2.GetEnumerator();
        DictionaryEntry d;
        while (demoEnum.MoveNext()) {
            d = (DictionaryEntry)demoEnum.Current;
            Console.WriteLine("Key = " + d.Key + ", Value = " + d.Value);
        }
    }
}

The output of the above code is −

StringDictionary1 elements...
a John
b Andy
c Tim
d Ryan
e Kevin
f Katie
g Brad

StringDictionary2 key-value pairs...
Key = 1, Value = A
Key = 2, Value = B
Key = 3, Value = C
Key = 4, Value = D
Key = 5, Value = E

Using GetEnumerator() with Numbers

Here's another example showing enumerator usage with numeric string keys −

using System;
using System.Collections;
using System.Collections.Specialized;

public class Demo {
    public static void Main() {
        StringDictionary strDict = new StringDictionary();
        strDict.Add("1", "One");
        strDict.Add("2", "Two");
        strDict.Add("3", "Three");
        strDict.Add("4", "Four");
        
        Console.WriteLine("StringDictionary key-value pairs...");
        IEnumerator demoEnum = strDict.GetEnumerator();
        DictionaryEntry d;
        while (demoEnum.MoveNext()) {
            d = (DictionaryEntry)demoEnum.Current;
            Console.WriteLine("Key = " + d.Key + ", Value = " + d.Value);
        }
    }
}

The output of the above code is −

StringDictionary key-value pairs...
Key = 1, Value = One
Key = 2, Value = Two
Key = 3, Value = Three
Key = 4, Value = Four

Key Points

• StringDictionary automatically converts all keys to lowercase during storage.

• The GetEnumerator() method returns an IEnumerator object.

• Each iteration returns a DictionaryEntry object with Key and Value properties.

• You can also use foreach loop directly on StringDictionary for simpler iteration.

Conclusion

The GetEnumerator() method provides a way to iterate through StringDictionary elements using the IEnumerator interface. This method is useful when you need explicit control over iteration, though the foreach loop offers a more convenient alternative for most scenarios.