Understanding Encapsulation in OOP

what is the output :

class Box {

private:

int width;

public:

void setWidth(int w)

{ width = w; }

int getWidth()

{ return width; } };

int main() {

Box b; b.setWidth(10);

cout << "Width of box: " << b.getWidth() << endl; return 0; }

• Compilation error

• Width of box: 0

• Width of box: 10

• Runtime error

What is the main purpose of using private access specifier in the code below?

class Car {

private:

int speed;

public:

void setSpeed(int s) { speed = s; }

int getSpeed() { return speed; } };

• To prevent the direct modification of speed from outside the class

• To allow direct access to the speed variable

• To allow the speed variable to be public

• To implement function overloading for setSpeed

What is the purpose of the private access specifier in the following code?

class Rectangle {

private:

int length;

public:

void setLength(int len) { length = len; }

int getLength() { return length; } };

• To allow direct access to the length variable from outside the class

• To make sure the length variable cannot be modified directly from outside the class

• To enable inheritance from the Rectangle class

• To allow multiple constructors

What is the difference between encapsulation and abstraction?

• Encapsulation is about creating user interfaces, while abstraction is about data storage.

• Encapsulation allows for multiple inheritance, whereas abstraction restricts it.

• Encapsulation focuses on data hiding and bundling, while abstraction focuses on simplifying complex systems by exposing only the essential features.

• Encapsulation is only used in object-oriented programming, while abstraction is used in all programming paradigms.

Which of the following best describes encapsulation in C++?

• A process of defining the blueprint of an object

• A mechanism to combine data and functions that operate on that data into a single unit

• A way to inherit properties from one class to another

• A feature that allows a function to be defined multiple times with different parameters

In the following program, what happens if you try to access balance directly from main()?

class Bank {

private:

double balance;

public:

void deposit(double amount) { balance += amount; } };

int main() { Bank b; b.deposit(500.00);

cout << b.balance << endl;

return 0; }

• The program will compile and print the balance

• The program will throw a runtime error

• The program will fail to compile due to the direct access of the private member

• The balance will be printed as 500.00 without any issue

What will happen if you try to access the length variable directly from outside the Rectangle class?

class Rectangle {

private:

int length;

public:

void setLength(int len) { length = len; }

int getLength() { return length; } };

• The program will compile and allow access to length

• The program will throw a runtime error

• The program will fail to compile due to the direct access of the private member

• The length will be printed without any issue

What is the effect of using the public access specifier in the following code?

class Employee {

public:

int id;

void setId(int empId) { id = empId; }

};

• It allows the id variable to be accessed from outside the class

• It restricts access to the id variable from outside the class

• It allows the id variable to be modified only through member functions

• It prevents the creation of multiple instances of the Employee class

Which of the following statements about access specifiers in C++ is true?

• Private members can be accessed directly from any function in the program

• Protected members can be accessed by derived classes

• Public members cannot be accessed from outside the class

• Public members can be accessed by any function within the same class only