Mastering C# Collections: A Comprehensive Guide Understanding C# collections is crucial for efficient data management. This guide explores the three primary categories of collection classes: System.Collections.Generic, System.Collections, and System.Collections.Concurrent. Learn about generic collections, non-generic collections, and thread-safe collections, including List, Stack, Queue, SortedList, ArrayList, Hashtable, ConcurrentStack, ConcurrentQueue, and ConcurrentDictionary.

Unlocking the Power of C# Collections

Understanding C# Collections

In C#, collections are classes that simplify working with groups of objects. These classes provide a robust way to store, manipulate, and retrieve data. There are three primary categories of collection classes in C#: System.Collections.Generic, System.Collections, and System.Collections.Concurrent.

Generic Collections: Precision and Type Safety

The System.Collections.Generic classes enable you to create generic collections, which store type-compatible data elements. This means you can’t mix and match different data types in the same collection. A prime example of a generic class is List, which allows you to define the type of data it will hold.

Exploring System.Collections.Generic Classes

Within the System.Collections.Generic namespace, you’ll find several essential classes:

List Class: Dynamic and Versatile

The List class stores multiple elements of the same data type, accessible via indexes. You can add, insert, and remove elements, and dynamically adjust the list’s size.

Stack Class: Last In, First Out

The Stack class is a generic collection that stores data elements of the same type in a Last In, First Out (LIFO) manner. You can perform operations like pushing and popping elements using methods.

Queue Class: First In, First Out

The Queue class stores objects in a First In, First Out (FIFO) manner, where elements are inserted at one end and removed from the other. You can add and remove elements using methods like Enqueue and Dequeue.

SortedList Class: Key-Value Pairs

The SortedList class is an array of key-value pairs sorted in a specific order. Each key must be unique, and you can access elements using these keys.

Non-Generic Collections: Flexibility and Versatility

The System.Collections classes allow you to create non-generic collections, which can store data elements of multiple types. These classes are part of the System.Collections namespace.

ArrayList Class: Resizable Arrays

The ArrayList class is non-generic, enabling you to store elements of multiple data types. It provides resizable arrays, allowing duplicate elements and supporting sorting.

Hashtable Class: Key-Value Pairs with Hash Codes

The Hashtable class is also non-generic, consisting of key-value pairs managed using hash codes. Keys cannot be null, but values can be.

Thread-Safe Collections: Ensuring Concurrent Access

The System.Collections.Concurrent classes provide thread-safe collection classes, essential for scenarios where multiple threads access the same collection. Thread safety ensures that code executes correctly, even when accessed concurrently.

ConcurrentStack, ConcurrentQueue, and ConcurrentDictionary

These classes guarantee thread safety, making them ideal for multithreaded environments. When multiple threads are involved, it’s recommended to use System.Collections.Concurrent classes over System.Collections and System.Collections.Generic classes.