Object-Oriented Programming & Class Design Flashcards

What is a friend function in C++?

Answer: A non-member function granted access to a class's private and protected members

A friend function is declared inside a class with the 'friend' keyword and can access private and protected members despite not being a member itself.

In the context of C++ class design, what does 'encapsulation' primarily mean?

Answer: Bundling data and methods that operate on that data together while hiding internal details

Encapsulation is the OOP principle of combining data and the functions that manipulate it into a class while restricting direct access to internal state.

What is the purpose of a move constructor introduced in C++11?

Answer: To transfer ownership of resources from a temporary object without copying

A move constructor transfers resources (like heap memory) from an expiring object (rvalue) to a new object, avoiding expensive deep copies.

Which operator must always be overloaded as a member function in C++?

Answer: operator=

The copy assignment operator (operator=) must be overloaded as a non-static member function because its left operand must be an lvalue of the class type.

What is a vtable (virtual table) in C++?

Answer: A runtime lookup table of function pointers used to resolve virtual function calls

A vtable is a per-class table of pointers to virtual functions, enabling the runtime dispatch that powers polymorphism.

What does 'final' do when applied to a C++11 class?

Answer: Prevents the class from being used as a base class

Declaring a class 'final' prohibits other classes from inheriting from it, locking the class hierarchy at that point.

Which of the following is true about static member variables in C++?

Answer: A static member variable is shared across all instances of the class

A static member variable belongs to the class itself rather than any individual instance, so all objects share a single copy.