What are union types in C# 15?

Union types let a variable hold exactly one type from a fixed set, like `string | int`, with compiler-enforced exhaustive checks via switch.

How do I use C# 15 union types in .NET 11?

Install .NET 11 Preview 2 SDK, target net11.0, declare as `TypeA | TypeB`, switch on it. Works in VS 2026 Insider.

Do union types replace object or dynamic in C#?

They offer a safer alternative for known type sets, but object/dynamic stick around for open-ended cases.

💻 Programming Languages

C# 15 Union Types: The End of Tedious Type Checks in .NET 11

Tired of endless if-else chains unwrapping mystery objects? C# 15's union types in .NET 11 fix that nightmare, handing developers type-safe flexibility that screams future-proof.

theAIcatchup Apr 09, 2026 4 min read

C# code snippet showing union types switch vs if-else chains

⚡ Key Takeaways

Union types eliminate if-else type unwrapping, boosting safety and readability. 𝕏
Compiler enforces handling all cases, slashing runtime errors in APIs and parsers. 𝕏
Opt-in feature in .NET 11 Preview 2; GA November 2026 — try it now for future-proof code. 𝕏

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theAIcatchup

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#.NET 11 #C# 15 #C# Features #type safety #union types

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