Classes, Inheritance, and Object-Oriented Concepts in C++

Question 1

What command is used to link a C++ object file?

Answer 1

g++ MyClass.o -o MyProgram

Question 2

What is the significance of the C++ Standard version 2020?

Answer 2

Introduced concepts and ranges

Question 3

What feature does setw provide in C++?

Answer 3

Sets the width of the next output field

Question 4

What does the using namespace std; statement do?

Answer 4

Allows access to the standard namespace

Question 5

What is the principle of modularity in C++?

Answer 5

Code organized into classes/files

Question 6

Define abstraction in the context of C++.

Answer 6

Hide unnecessary details

Question 7

What does encapsulation mean in C++?

Answer 7

Private data, accessed only via class

Question 8

What is extensibility in C++?

Answer 8

Reuse and build on top of existing code

Question 9

Define polymorphism in C++.

Answer 9

Same interface, different behavior

Question 10

What is inheritance in C++?

Answer 10

Child class inherits from parent class

Question 11

What is the syntax to define a class in C++?

Answer 11

class ClassName { /* members */ };

Question 12

What does a constructor do in C++?

Answer 12

Called automatically when an object is created

Question 13

What is the role of a destructor in C++?

Answer 13

Called automatically when an object goes out of scope

Question 14

How do you declare a parameterized constructor?

Answer 14

ClassName(int i, int j)

Question 15

Fill in the blank: A parameterized constructor creates objects with _______.

Answer 15

Initial values

Question 16

What is the rule for default parameters in C++?

Answer 16

Once a default is used, all following parameters must have one too!

Question 17

What does the scope resolution operator :: do?

Answer 17

Defines class methods outside the class

Question 18

True or False: You should use malloc() and free() in C++.

Answer 18

False

Question 19

What is the correct way to allocate memory for an integer in C++?

Answer 19

int* p = new int(42);

Question 20

What is the difference between a reference and a pointer in C++?

Answer 20

Reference: Implicit dereference; Pointer: * required

Question 21

What is the syntax for passing by reference?

Answer 21

void function(int& x)

Question 22

Fill in the blank: The this pointer is used to refer to the _______.

Answer 22

Current object inside its method

Question 23

What is a copy constructor in C++?

Answer 23

Creates a new object from another existing one

Question 24

Why is a custom copy constructor necessary?

Answer 24

Default copy = shallow copy (bad for pointers!)

Question 25

What is a static member in a C++ class?

Answer 25

Value is shared across all instances

Question 26

How do you access a static member in C++?

Answer 26

ClassName::memberName

Question 27

What are the two main types of constructors in C++?

Answer 27

* Default constructor * Parameterized constructor

Question 28

What happens when you use new in C++?

Answer 28

Calls constructor

Question 29

What happens when you use delete in C++?

Answer 29

Calls destructor

Question 30

How do you define a member function outside the class?

Answer 30

ReturnType ClassName::functionName() { /* body */ }

Question 31

Fill in the blank: In C++, the this pointer allows method _______.

Answer 31

Chaining

Question 32

What is Inheritance?

Answer 32

Inheritance lets a class acquire properties (variables & methods) from another class.

Question 33

What is the analogy used to explain Inheritance?

Answer 33

* Product → base class (general) * PackagedProduct → derived class (adds packaging) * LabelledProduct → derived class (adds barcode, label)

Question 34

What is the syntax for defining a derived class in C++?

Answer 34

class Derived : access Base { // new or extended features };

Question 35

Provide an example of a derived class in C++.

Answer 35

class MySpecialString : public Stringy { char type; };

Question 36

How are base class members inherited with respect to access specifiers?

Answer 36

* public: accessible * protected: accessible * private: not accessible

Question 37

What should you use for most inheritance scenarios?

Answer 37

Use public inheritance unless intentionally hiding things.

Question 38

What are the access levels for members in inheritance?

Answer 38

* public: accessible * protected: accessible * private: not accessible

Question 39

What is the order of execution for constructors and destructors?

Answer 39

Constructors run top-down (base → derived), Destructors run bottom-up (derived → base).

Question 40

What is the output order of constructors and destructors in the provided example?

Answer 40

Base, Derived, Bye Derived, Bye Base

Question 41

How do you pass parameters to a base class constructor?

Answer 41

Use the initializer list in the derived class constructor.

Question 42

What is chain inheritance?

Answer 42

class base { ... }; class derived1 : public base { ... }; class derived2 : public derived1 { ... };

Question 43

What is the order of construction and destruction in chain inheritance?

Answer 43

* Construct: base → derived1 → derived2 * Destruct: derived2 → derived1 → base

Question 44

What is multiple inheritance?

Answer 44

class derived : public base1, public base2 { ... };

Question 45

What issue may arise from multiple inheritance?

Answer 45

Ambiguity if both base classes have similar members.

Question 46

What is the Diamond Problem in inheritance?

Answer 46

Derived class gets two copies of the base class member.

Question 47

How can you resolve the Diamond Problem?

Answer 47

* Use scope resolution * Use virtual base classes

Question 48

What are virtual base classes?

Answer 48

Ensure only one copy of the base is inherited.

Question 49

What is the purpose of virtual member functions?

Answer 49

Enables polymorphism.

Question 50

What is the result of dynamic dispatch using virtual functions?

Answer 50

Function is bound at runtime, not compile time.

Question 51

What is an abstract class?

Answer 51

A class that has at least one pure virtual method.

Question 52

What happens if you try to instantiate an abstract class?

Answer 52

It results in a compilation error.

Question 53

Summarize the key ideas of inheritance.

Answer 53

* Inheritance: Let one class use another's members * Access Levels: public / protected / private * Constructor Order: Base → Derived * Multiple Inheritance: Can cause conflicts – use virtual * Virtual Function: Enables dynamic dispatch * Abstract Class: Has at least one pure virtual method * Diamond Problem: Fixed using virtual base classes