Topic 7. Classes and objects: data members, member functions, constructors, destructors, and encapsulation

Goal: learn to apply the concepts of the topic “Classes and objects: data members, member functions, constructors, destructors, and encapsulation” in console projects; justify invariants and the contracts of operations; test both ordinary and edge cases.

Lecture contents

1. Class, invariant, and constructors — State, behavior, and the class invariant · Constructors and the member initializer list
2. Composition and object lifetime — Composition and splitting code into files · Object lifetime and the destructor
3. const, static, and aggregates — Constness, this, and observing state · Static members and nested types · Aggregates and designated initialization
4. Designing and testing a class — Designing a minimal interface · Diagnosing and checking invariants · Scenario walkthrough: a seat reservation class
5. Case studies and common mistakes — Reference lifetime, member objects, and failed construction · Checking an interface with a contract table · The boundary between a constructor and user input · When an accessor grants too much freedom · A review case: an initialization error

Practice and review

• Practice — 3 worked examples with full code and output
• Tasks — 30 variants, each with tasks at three difficulty levels
• Summary — conclusions, self-check questions, and useful links