C# Collections

In C#, collection represents group of objects. By the help of collections, we can perform various operations on objects such as

• store object
• update object
• delete object
• retrieve object
• search object, and
• sort object

In sort, all the data structure work can be performed by C# collections.

We can store objects in array or collection. Collection has advantage over array. Array has size limit but objects stored in collection can grow or shrink dynamically.

Types of Collections

There are 3 ways to work with collections. The three namespaces are given below:

• System.Collections.Generic classes
• System.Collections classes (Now deprecated)
• System.Collections.Concurrent classes

System.Collections.Generic classes

The System.Collections.Generic namespace has following classes:

• List
• Stack
• Queue
• LinkedList
• HashSet
• SortedSet
• Dictionary
• SortedDictionary
• SortedList

System.Collections classes

These classes are legacy. It is suggested now to use System.Collections.Generic classes. The System.Collections namespace has following classes:

• ArrayList
• Stack
• Queue
• Hashtable

System.Collections.Concurrent classes

The System.Collections.Concurrent namespace provides classes for thread-safe operations. Now multiple threads will not create problem for accessing the collection items.

The System.Collections.Concurrent namespace has following classes:

• BlockingCollection
• ConcurrentBag
• ConcurrentStack
• ConcurrentQueue
• ConcurrentDictionary
• Partitioner
• Partitioner
• OrderablePartitioner