B CompE Bachelor of Computer Engineering Bachelor of Computer Engineering Object Oriented Programming 4

Question 1

In the Observer design pattern, what role does the 'Subject' play?

Accepted Answer

It stores a list of observers and notifies them of state changes

Answer

The Subject (or Publisher) maintains references to its observers and broadcasts notifications whenever its state changes.

Question 2

What is the difference between aggregation and composition in OOP?

Accepted Answer

In composition the child cannot exist independently; in aggregation it can

Answer

Composition is a strong ownership relationship where the part's lifetime depends on the whole, while aggregation is a weaker association where parts can exist independently.

Question 3

What does the Liskov Substitution Principle (LSP) require?

Accepted Answer

Objects of a subclass should be replaceable for objects of the parent class without breaking correctness

Answer

LSP states that wherever a base type is expected, a subtype can be used without altering the correctness of the program.

Question 4

Which keyword in C++ ensures a method cannot be overridden in derived classes?

Accepted Answer

final

Answer

In C++11 and later, the 'final' specifier on a virtual function prevents any further derived class from overriding that function.

Question 5

What is a pure virtual function in C++?

Accepted Answer

A virtual function with no body, declared with = 0

Answer

A pure virtual function (= 0) makes its class abstract; derived classes must provide an implementation unless they too are abstract.

B CompE Bachelor of Computer Engineering Practice Test

B CompE Bachelor of Computer Engineering Practice Test

B CompE Bachelor of Computer Engineering Bachelor of Computer Engineering Object Oriented Programming 4