oop intro class & object

1. What is an Object in C++?

• A data structure

• A data type

• A function

• A variable of a class type

Answer explanation

An object is an instance of a class. It is created based on the class definition and can access the class's member functions and attributes.

2. What does the public keyword do in a C++ class?

• It defines a member function inside the class

• It allows member variables and functions to be accessed from outside the class

• It hides the member variables from outside access

• It allows member variables to be private

3. Which of the following is the correct syntax to define a class in C++?

• class: Car {}

• class Car {};

• Car class {}

• class Car; {}

Consider the following code: What is the output?

• Hello, OOP!

• Error: display function is private

• Error: No object created

• No output

Answer explanation

The display function is public, so it can be accessed by the object obj created in the main function.

Which of the following is a valid way to create an object of a class named 'Bike'?

• Bike myBike;

• new Bike();

• Bike myBike();

• myBike Bike;

How do you define a member function outside a class?

• ReturnType ClassName::FunctionName()

• ReturnType FunctionName::ClassName()

• ClassName::ReturnType FunctionName()

• ClassName.FunctionName()

Answer explanation

The correct way to define a member function outside a class is by using the scope resolution operator :: to indicate that the function belongs to a particular class.

What is the output of the following code?

• 20

• 10

• 0

• Error

Answer explanation

The function modifyX receives the object obj by value, creating a copy. Changes made inside the function do not affect the original object.

How can you modify an object's attributes inside a function using pass by reference?

• Use * before the object

• Use & before the object in the function parameter

• Use . before the attribute

• Pass the object by value

Answer explanation

Use & before the object in the function parameter
Explanation: Passing an object by reference using & allows direct modification of the original object's attributes.

What is the difference between passing an object by value and by reference?

• By value creates a copy; by reference passes the original object

• By reference creates a copy; by value passes the original object

• Both create a copy of the object

• Both pass the original object

What is the keyword used to access members of an object in C++?

• ::

• ->

• .

• :

Answer explanation

The dot operator (.) is used to access member variables and functions of an object.