Stage 1 · Lesson 7 of 7
Exceptions and disposing resources
When code meets a situation it cannot handle, it an exception, and the nearest matching catch up the call stack deals with it. Catch only exceptions you can do something useful about, such as a concurrency conflict you turn into a 409 response.
Let everything else travel up to one global handler, which you will add in the production stage. using and await using make sure connections, files and are disposed, even when an exception is thrown. Custom exceptions such as InsufficientFundsException make business failures clear.
Exceptions are for exceptional cases: validation failures are better returned as than thrown on every bad request.
Common trapthrow ex;, which resets the stack and hides where the problem started. Write throw; instead.
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Resources for this stage
Start with· follow one of these
- GuideFreeLearn C#
Microsoft · Beginner
Free official C# path: syntax, types, classes, collections and exceptions with in-browser exercises
- GuideFree.NET documentation
Microsoft
The official .NET docs: start with the CLI overview, project files and the C# language tour
Practise
Keep handy
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The features that ship with .NET 10: extension members, the field keyword and null-conditional assignment
Object-oriented design worked through on real systems: classes, relationships and responsibilities
- Refactoring.Guru: Design PatternsGo deeper
Free: the classic design patterns explained with diagrams and C# examples