AMCAT Object-Oriented Programming Concepts 3

Question 1

In OOP, 'composition' refers to:

Accepted Answer

A class being built from objects of other classes as parts

Answer

A class inheriting from multiple parent classes

Answer

Defining multiple constructors in a class

Answer

A method calling another method in the same class

Question 2

What is the key difference between aggregation and composition in OOP?

Accepted Answer

Composition implies stronger ownership where child objects cannot exist independently; aggregation is a weaker 'uses-a' relationship

Answer

Aggregation implies a stronger ownership — the child cannot exist without the parent; composition implies a weaker relationship

Answer

There is no difference between aggregation and composition

Answer

Aggregation uses inheritance; composition uses interfaces

Question 3

A virtual function in C++ is a member function that:

Accepted Answer

Is declared in the base class and overridden in derived classes, resolved at runtime

Answer

Cannot be overridden in derived classes

Answer

Is resolved at compile time using the object type

Answer

Can only be defined inside an abstract class

Question 4

Which design pattern ensures that only one instance of a class is created throughout the application's lifetime?

Accepted Answer

Singleton Pattern

Answer

Factory Pattern

Answer

Observer Pattern

Answer

Decorator Pattern

Question 5

Which of the following is a characteristic of a pure virtual function (in C++) or abstract method (in Java/C#)?

Accepted Answer

It must be overridden in every concrete subclass

Answer

It provides a default implementation that subclasses may optionally override

Answer

It can only be called on the base class directly

Answer

It is defined using the 'static' keyword

Question 6

What does 'coupling' refer to in the context of OOP design?

Accepted Answer

The degree of interdependence between software modules or classes

Answer

The number of methods in a class

Answer

The ability of a class to inherit from multiple parents

Answer

The number of objects a class can create

Question 7

In OOP, the Open/Closed Principle states that software entities should be:

Accepted Answer

Open for extension and closed for modification

Answer

Open for modification and closed for extension

Answer

Open for both modification and extension

Answer

Closed for both modification and extension