C# Collection
The Collection class is a class specifically used for data storage and retrieval. These classes provide support for stacks, queues, lists, and hash tables. Most collection classes implement the same interface.
The Collection class serves different purposes, such as dynamically allocating memory for elements, accessing list items based on indexes, etc. These classes create collections of objects of the Object class. In C#, the Object class is the base class for all data types.
Various collection classes and their usage
The following are various commonly used System.Collection namespace classes. Click the link below for details.
| Class | Description and Usage |
|---|---|
| Dynamic Array (ArrayList) | It represents An ordered collection of objects that can be individually indexed. It basically replaces an array. However, unlike arrays, where you can add and remove items at specified locations using indexing, a dynamic array will automatically resize it. It also allows dynamic memory allocation, addition, searching, and sorting of items in lists. |
| Hashtable | It uses keys to access elements in the collection. When you access an element using a key, a hash table is used, and you can identify a useful key value. Each item in the hash table has a key/value pair. Keys are used to access items in the collection. |
| Sorted List (SortedList) | It can use keys and indexes to access items in the list . Sorted lists are a combination of arrays and hash tables. It contains a list of items that can be accessed using a key or index. If you access items using indexes, it's a dynamic array (ArrayList), if you access items using keys, it's a hashtable (Hashtable). Items in a collection are always sorted by key value. |
| Stack (Stack) | It represents a last-in-first-out collection of objects. Use a stack when you need last-in-first-out access to items. When you add an item to the list, it is called pushing the element, and when you remove an item from the list, it is called popping the element. |
| Queue (Queue) | It represents a first-in-first-out object collection. Use a queue when you need first-in, first-out access to items. When you add an item to the list, it is called enqueuing, and when you remove an item from the list, it is called dequeuing. |
| BitArray | It represents a binaryarray represented using values 1 and 0. Use a dot array when you need to store bits, but don't know the number of bits in advance. You can access items from a point array collection using integer indexing, with indexing starting at zero. |
