C#

Write robust C# avoiding null traps, async deadlocks, and LINQ pitfalls.

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Pattern checks against bundled files.

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openclaw skills install csharp

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`

?. 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