Specialized Collections

Introduction to Specialized Collections

In C#, the System.Collections.Specialized namespace provides specialized and strongly-typed collections. These collections are designed for specific tasks that are not directly supported by the general-purpose collection classes. In this tutorial, we will explore various types of specialized collections in C#.

ListDictionary

The ListDictionary is a collection that represents a linked list of key/value pairs. This type of collection is optimal for collections that typically contain 10 items or fewer.

Here is how to create and use a ListDictionary:

ListDictionary listDictionary = new ListDictionary();

listDictionary.Add("1", "One");
listDictionary.Add("2", "Two");

foreach (DictionaryEntry entry in listDictionary)
{
    Console.WriteLine($"{entry.Key}: {entry.Value}");
}

HybridDictionary

The HybridDictionary is a collection that starts as a ListDictionary and becomes a Hashtable when the number of elements exceeds a certain threshold.

Here is how to create and use a HybridDictionary:

HybridDictionary hybridDictionary = new HybridDictionary();

hybridDictionary.Add("1", "One");
hybridDictionary.Add("2", "Two");

foreach (DictionaryEntry entry in hybridDictionary)
{
    Console.WriteLine($"{entry.Key}: {entry.Value}");
}

OrderedDictionary

The OrderedDictionary is a collection that maintains the insertion order of elements.

Here is how to create and use an OrderedDictionary:

OrderedDictionary orderedDictionary = new OrderedDictionary();

orderedDictionary.Add("1", "One");
orderedDictionary.Add("2", "Two");

foreach (DictionaryEntry entry in orderedDictionary)
{
    Console.WriteLine($"{entry.Key}: {entry.Value}");
}

StringCollection

The StringCollection is a collection that contains a collection of String objects.

Here is how to create and use a StringCollection:

StringCollection stringCollection = new StringCollection();

stringCollection.Add("One");
stringCollection.Add("Two");

foreach (string str in stringCollection)
{
    Console.WriteLine(str);
}

StringDictionary

The StringDictionary is a collection with keys and values of type String.

Here is how to create and use a StringDictionary:

StringDictionary stringDictionary = new StringDictionary();

stringDictionary.Add("1", "One");
stringDictionary.Add("2", "Two");

foreach (DictionaryEntry entry in stringDictionary)
{
    Console.WriteLine($"{entry.Key}: {entry.Value}");
}

NameValueCollection

The NameValueCollection is a collection that associates String keys with collections of String values.

Here is how to create and use a NameValueCollection:

NameValueCollection nameValueCollection = new NameValueCollection();

nameValueCollection.Add("Numbers", "One");
nameValueCollection.Add("Numbers", "Two");

foreach (string key in nameValueCollection.Keys)
{
    Console.WriteLine($"{key}: {string.Join(", ", nameValueCollection.GetValues(key))}");
}

Each of these collections serves a different purpose and has its own advantages. The choice of which specialized collection to use depends on the specific requirements of the application.

In summary, specialized collections in C# are a powerful tool for handling data. They offer unique features that are not available in general-purpose collections. Understanding these collections and knowing when to use each one can greatly enhance your C# programming skills.

Happy coding!