C#

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name: C# slug: csharp version: 1.0.1 description: Write robust C# avoiding null traps, async deadlocks, and LINQ pitfalls. metadata: {"clawdbot":{"emoji":"💜","requires":{"bins":["dotnet"]},"os":["linux","darwin","win32"]}}

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Quick Reference

| Topic | File | |-------|------| | Null reference, nullable types | nulls.md | | Async/await, deadlocks | async.md | | Deferred execution, closures | linq.md | | Value vs reference, boxing | types.md | | Iteration, equality | collections.md | | IDisposable, using, finalizers | dispose.md |

Critical Rules

?. and ?? prevent NRE but ! overrides warnings — still crashes if null

.Result or .Wait() on UI thread — deadlock, use await or ConfigureAwait(false)

LINQ is lazy — query.Where(...) doesn't execute until iteration

Multiple enumeration of IEnumerable — may re-query database, call .ToList() first

Closure captures variable, not value — loop variable in lambda captures last value

Struct in async method — copied, modifications lost after await

String comparison culture — StringComparison.Ordinal for code, CurrentCulture for UI

GetHashCode() must be stable — mutable fields break dictionary lookup

Modifying collection while iterating — throws, use .ToList() to iterate copy

decimal for money — float/double have precision loss

readonly struct prevents defensive copies — use for performance

sealed prevents inheritance — enables devirtualization optimization