CSharp-Coder

Learn all C# 13 new features with practical code examples. Params collections, partial properties, Lock type, and more — upgrade your .NET 9 skills today. C# 13 shipped with .NET 9 in November 2024, and by mid-2026 most teams have either adopted it or are planning their upgrade. Whether you're already using it in production or still evaluating the jump, this guide covers every C# 13 new feature with practical, runnable code examples so you can see exactly what changed and why it matters. This isn't a changelog copy-paste. We'll walk through each feature, explain the problem it solves, show before-and-after code, and flag the gotchas you'll hit in real projects. 1. params Collections — The Biggest Quality-of-Life Win in C# 13 Before C# 13, the params keyword only worked with arrays. That meant every call allocated a new array on the heap, even if the method just iterated over the values once. C# 13 lifts that restriction: params now works with any colle...