CSharp-Coder

Learn C# interfaces vs abstract classes with real code examples. Master when to use each, best practices, and common pitfalls. Start coding smarter today. If you have ever sat in a technical interview or stared at a design decision in Visual Studio, you have hit this question: C# interface vs abstract class — which one should you use? It is one of the most searched C# topics for a reason. Both let you define contracts and share behavior, both power polymorphism, and both look deceptively similar at first glance. But choosing the wrong one leads to rigid, hard-to-maintain code. In this complete guide, we will break down the real difference between interfaces and abstract classes in C#, show runnable code examples, cover modern C# features like default interface methods, and give you a clear decision framework. Whether you are a beginner learning C# OOP concepts or a senior engineer refining your architecture, this article will make the choice obvious. What Is an Interface in ...

Master C# pattern matching with this complete guide. Learn switch expressions, property patterns, and list patterns with runnable code examples. Start coding today! C# pattern matching is one of the most powerful features added to the language in recent years, and if you are not using it yet, your code is probably more verbose and harder to read than it needs to be. In this complete guide to C# pattern matching , you will learn how to use switch expressions, property patterns, list patterns, and more — with practical, runnable code examples you can drop straight into your projects. Whether you are a beginner searching for how pattern matching works, an intermediate developer looking for best practices, or a senior engineer wanting advanced techniques, this tutorial has you covered. What Is Pattern Matching in C#? Pattern matching is a technique that tests whether a value has a certain shape , and when it does, extracts information from it. Instead of writing long chains of if...

Master C# collections performance: List vs Dictionary vs HashSet vs Queue with Big-O tables, real benchmarks, and code examples. Pick the right one today. Choosing the right data structure is one of the highest-leverage performance decisions you can make in .NET — and C# collections are where most of those decisions happen. Should you use a List<T> or a Dictionary<TKey, TValue> ? When does a HashSet<T> beat both? And where does Queue<T> fit in? In this guide, we'll compare the four most-used collections in C# with Big-O complexity tables, runnable benchmark code, and clear rules for when to use each. By the end, you'll be able to justify your collection choice in a code review — not just guess. Why C# Collections Performance Matters Every collection type in .NET makes a trade-off. List<T> gives you cheap indexed access and great iteration speed but slow lookups by value. Dictionary<TKey, TValue> gives you near-instant lookups...

Master LINQ in C# with this hands-on C# LINQ tutorial. 10 practical, runnable examples with best practices and pitfalls. Start querying smarter today! If you write C# for a living, LINQ is not optional — it is the standard way to filter, transform, and aggregate data in .NET. This C# LINQ tutorial walks you through 10 practical examples every developer must know, from simple filtering with Where to grouping, joining, and flattening collections. More importantly, we explain why each operator works the way it does, so you understand deferred execution, avoid the classic multiple-enumeration trap, and write queries that are both readable and fast. All examples run on modern .NET (6, 8, or 10) and use this shared sample data, so you can paste them straight into a console app or dotnet run a top-level program: public record Employee(int Id, string Name, string Department, decimal Salary, int Age); List<Employee> employees = new() { new(1, "Alice", "E...

Learn C# pattern matching with this complete guide covering switch expressions, property patterns & list patterns. Runnable examples & best practices — start now! C# pattern matching is one of the most powerful features added to the language in recent years, and it fundamentally changes how you write conditional logic. Instead of long, nested if-else chains and clunky type checks, C# pattern matching lets you test the shape, type, and values of data in a single, readable expression. In this complete guide, you'll learn everything from basic type patterns to advanced switch expressions, property patterns, and list patterns — with runnable C# code examples you can drop straight into your projects. Whether you're a beginner searching for how to use the switch statement, an intermediate developer looking for best practices, or a senior engineer exploring advanced pattern matching in C#, this tutorial covers it all. Let's dig in. What Is C# Pattern Matchin...

Learn C# unit testing with xUnit and test-driven development in this complete tutorial. Master TDD, Fact, Theory, mocking, and best practices. Start now! If you want to write reliable, bug-resistant .NET applications, mastering C# unit testing is one of the highest-return skills you can develop. In this complete tutorial you'll learn C# unit testing with xUnit — the most popular testing framework in the modern .NET ecosystem — and how to combine it with test-driven development (TDD) to design cleaner, more maintainable code. Whether you're a beginner searching for "how to write unit tests in C#," an intermediate developer looking for xUnit best practices, or a senior engineer refining your TDD workflow, this guide has you covered with practical, runnable examples. What Is C# Unit Testing and Why Does It Matter? A unit test verifies that a small, isolated piece of code — usually a single method — behaves exactly as expected. Instead of manually running...

Learn C# source generators to automate code generation at compile time. Step-by-step tutorial with examples, best practices, and real-world use cases. What Are C# Source Generators? C# source generators let you inspect your code during compilation and automatically produce new C# files that become part of your project — no manual coding, no runtime reflection, no post-build scripts. Introduced with .NET 5 and Roslyn, they run inside the compiler itself, giving you a compile-time hook to eliminate boilerplate at the source. If you have ever written the same property-changed notification, the same mapping method, or the same serialization logic across dozens of classes, source generators in C# solve that problem permanently. The compiler writes the code for you, every time you build. In this tutorial you will build a working source generator from scratch, understand the API surface, learn the patterns that scale, and avoid the mistakes that waste hours of debugging. Why Us...