28 Lecture

What is the purpose of virtual functions in C++? A. To achieve static polymorphism B. To achieve dynamic polymorphism C. To improve code readability D. To increase program performance Answer: B Which keyword is used to declare a function as virtual in C++? A. static B. virtual C. dynamic D. polymorphic Answer: B In which class are virtual functions declared in C++? A. Base class B. Derived class C. Abstract class D. Static class Answer: A Which function is called when a virtual function is invoked through a base class pointer? A. Base class function B. Derived class function C. Default function D. Static function Answer: B What is a virtual function table (vtable) in C++? A. A table that stores the addresses of all virtual functions in a class hierarchy B. A table that stores the names of all virtual functions in a class hierarchy C. A table that stores the values of all virtual functions in a class hierarchy D. A table that stores the types of all virtual functions in a class hierarchy Answer: A Can a derived class override a non-virtual function of its base class in C++? A. Yes B. No Answer: A What is the syntax for providing a default implementation of a virtual function in C++? A. virtual void functionName() { ... } B. virtual void functionName() = 0; C. virtual void functionName() default; D. virtual void functionName() { ... } default; Answer: D What is the difference between a pure virtual function and a virtual function with a default implementation in C++? A. A pure virtual function has no implementation, while a virtual function with a default implementation does B. A pure virtual function cannot be called, while a virtual function with a default implementation can be C. A pure virtual function is declared with the = 0 syntax, while a virtual function with a default implementation is declared with the = default syntax D. There is no difference between the two Answer: A Can virtual functions be defined as private in a C++ class? A. Yes B. No Answer: A What is the purpose of a virtual destructor in C++? A. To improve program performance B. To allow objects to be destroyed properly in a class hierarchy C. To prevent memory leaks D. To allow objects to be cloned easily Answer: B

What is a virtual function in C++ and how is it declared? Answer: A virtual function is a function that can be overridden by a derived class. It is declared using the virtual keyword before the function prototype in the base class. What is the difference between a virtual function and a non-virtual function in C++? Answer: A virtual function can be overridden by a derived class, while a non-virtual function cannot be overridden. Can a virtual function be static or friend in C++? Answer: No, a virtual function cannot be static or friend in C++. What is the purpose of a pure virtual function in C++ and how is it declared? Answer: A pure virtual function is a virtual function that has no implementation in the base class and must be overridden by the derived class. It is declared using the syntax virtual void functionName() = 0; Can a virtual function be defined outside of its class in C++? Answer: Yes, a virtual function can be defined outside of its class in C++. Can a constructor or destructor be virtual in C++? Answer: Yes, a constructor or destructor can be virtual in C++. What is a virtual function table (vtable) in C++? Answer: A virtual function table is a table that stores the addresses of all virtual functions in a class hierarchy. What is the difference between early binding and late binding in C++? Answer: Early binding is when the function call is resolved at compile-time based on the type of the object pointer, while late binding is when the function call is resolved at runtime based on the type of the object pointed to. What is the difference between function overloading and function overriding in C++? Answer: Function overloading is when multiple functions have the same name but different parameters, while function overriding is when a derived class provides its own implementation of a virtual function in the base class. What is the purpose of a virtual destructor in C++? Answer: The purpose of a virtual destructor is to ensure that the destructor of the derived class is called when a derived class object is deleted through a pointer to the base class.