05.01 Objects And Classes - Quiz

Check your understanding

1. What is the main difference between a class and an object?

   • A class is written in Python, an object is written in Java
   • A class is a blueprint or template, an object is an instance created from that blueprint { data-correct }
   • A class contains methods, an object contains attributes
   • A class is larger than an object

2. When you write student.study("Math") in Python, what is happening?

   • You are defining a new method called study
   • You are creating a new class called student
   • You are sending a message to the student object to execute its study method { data-correct }
   • You are importing the Math module

3. In the following code, how many instances of the BankAccount class are created?

   class BankAccount:
       def __init__(self, balance):
           self.balance = balance
   
   acc1 = BankAccount(100)
   acc2 = BankAccount(200)
   acc3 = acc1
   

   • 1
   • 2 { data-correct }
   • 3
   • 4

4. What is an attribute in object-oriented programming?

   • A special type of method that returns a value
   • Data or properties that describe the state of an object { data-correct }
   • A way to create new objects
   • A type of loop used in classes

5. What does the self parameter represent in a Python method?

   • The class itself
   • The method being called
   • The specific instance (object) the method is being called on { data-correct }
   • All instances of the class

6. Which of the following best describes message passing in OOP?

   • Objects can only communicate through global variables
   • Objects communicate by calling each other’s methods { data-correct }
   • Objects can only communicate with objects of the same class
   • Objects communicate through direct memory access

7. What will be the output of this code?

   class Counter:
       def __init__(self):
           self.count = 0
   
       def increment(self):
           self.count += 1
           return self.count
   
   c1 = Counter()
   c2 = Counter()
   print(c1.increment())
   print(c2.increment())
   

   • 1, 1 { data-correct }
   • 1, 2
   • 2, 2
   • 0, 0

8. Which statement about classes and instances is correct?

   • A class can only have one instance
   • An instance can belong to multiple classes
   • A class is a blueprint, an instance is created from that blueprint { data-correct }
   • Classes and instances are the same thing

9. What is encapsulation in object-oriented programming?

   • Combining data and methods into a single unit { data-correct }
   • Making all data public
   • Separating data from methods
   • Converting objects to strings

10. Why is message passing important in OOP? (Select all that apply)

    • It allows objects to work together without knowing internal details { data-correct }
    • It makes code run faster
    • It provides better memory management
    • It enables encapsulation and modularity { data-correct }