C# interviews focus on OOP, CLR memory, LINQ, async/await, generics, and modern language features. Be ready to explain trade-offs with Java GC, C++ manual memory, and JavaScript dynamic typing.
Must-know topics
- Value vs reference types, boxing, and GC generations
- Classes, interfaces, records, and struct choices
- LINQ deferred execution and IEnumerable vs IQueryable
- async/await mechanics—avoid blocking .Result
- Nullable reference types and pattern matching
- Delegates, events, generics, and IDisposable
- dotnet CLI, assemblies, NuGet, and testing basics
Important interview questions and answers
- Q: Explain CLR in 30 seconds.
A: Loads assemblies, JIT-compiles IL to native code, manages the heap with a tracing GC, and provides the Base Class Library. - Q: string vs StringBuilder?
A: Immutable concatenation allocates many interim strings; StringBuilder mutates a buffer for heavy building. - Q: When not use C#?
A: Browser-first UI without Blazor, teams standardized on JVM-only stacks, or hard real-time with no GC tolerance.
Self-check
- List three C# topics you will review before interviews.
- How does async differ from Parallel.For for CPU work?
Tip: Be ready to explain value vs reference types, LINQ deferred execution, async/await, and GC basics—common screen topics.
Interview prep
- Must-know C# interview topics?
Value vs reference types, GC, LINQ deferred execution, async/await, generics, nullable references, and IDisposable.
- Explain CLR in 30 seconds?
Loads assemblies, JIT-compiles IL to native code, manages the heap with a tracing GC, and provides the Base Class Library.