Quiz

// 10 questions. Pass: >= 7.

// ===== Q1 =====
// What is the default access modifier for a class member in C#?
// A) public
// B) internal
// C) private
// D) protected

// ===== Q2 =====
// What does 'init' allow?
// A) Property settable only inside the constructor
// B) Property settable only during object initialisation
// C) Same as readonly
// D) Async initialisation

// ===== Q3 =====
// What does 'record' provide compared to 'class'?
// A) Value equality + ToString + Deconstruct + with-expressions
// B) Garbage-collected automatically
// C) Asynchronous methods
// D) None of the above

// ===== Q4 =====
// What does 'string?' mean (with nullable reference types enabled)?
// A) String can hold any value
// B) Compiler treats null as a legitimate value; warns on dereference
// C) Same as 'string'
// D) Means string of length 0 or 1

// ===== Q5 =====
// What's the difference between 'IEnumerable<T>' and 'IQueryable<T>'?
// A) IEnumerable executes in-memory; IQueryable defers + translates to SQL
// B) IQueryable is async; IEnumerable is sync
// C) They are the same
// D) IEnumerable cannot be ToList()d

// ===== Q6 =====
// What does 'await' do?
// A) Synchronously waits
// B) Returns a Task
// C) Suspends the method until the awaited task completes; resumes when ready
// D) Causes a deadlock

// ===== Q7 =====
// 'async void' should be used for:
// A) Any async method that doesn't return data
// B) Event handlers only
// C) Methods called from Main
// D) Never

// ===== Q8 =====
// What is the typical purpose of 'using' declarations (C# 8+)?
// A) Import namespaces
// B) Dispose IDisposable objects automatically at scope end
// C) Suppress warnings
// D) Inline a method

// ===== Q9 =====
// What does '?? ' (null-coalescing operator) do?
// A) Bitwise OR
// B) Returns left if not null; right otherwise
// C) Comparison
// D) Pattern matching

// ===== Q10 =====
// In ASP.NET Core, what is dependency injection registered via?
// A) Static class
// B) IServiceCollection in Program.cs (Configure / WebApplicationBuilder.Services)
// C) [Inject] attribute only
// D) DI is not supported

// ===== Answers =====
// 1. C — private is default for class members
// 2. B — init: only during object initialisation
// 3. A — record adds value equality, ToString, Deconstruct, with-expressions
// 4. B — nullable ref type; compiler tracks null
// 5. A — IQueryable defers + translates (e.g. to SQL via EF)
// 6. C — await suspends + resumes
// 7. B — async void only for event handlers
// 8. B — using disposes at scope end
// 9. B — null-coalescing
// 10. B — register via WebApplicationBuilder.Services

// ===== Patterns =====
// - Records for DTOs + value-shape types
// - Nullable refs enabled, treat warnings as errors
// - await Task.WhenAll for parallel async
// - DI everywhere; constructor injection

// ===== Pitfalls =====
// - .Result on Task (deadlocks)
// - async void (silent exceptions)
// - decimal vs double for money
// - Long LINQ chains in hot loops

// 3 questions per lesson.