Q and A

Here are some questions that interviewers may ask to test your basic knowledge of object oriented design principles.

What is a...

1. Class:

   • A class is a fundamental building block in object-oriented programming.
   • It serves as a blueprint for defining objects in software, containing properties and methods.
   • OOP allows for one class to inherit from another, facilitating code reuse.

2. Properties and Methods:

   • Properties are the attributes (nouns) of a class, defining characteristics like color, size, etc.
   • Methods are the behaviors (verbs) of a class, defining actions like fly(), eat(), etc.

3. Inheritance:

   • Inheritance allows a child class to use the methods and properties of a parent class.
   • Child classes inherit behavior from parent classes, facilitating code reuse and promoting a hierarchical structure.
   • For example, a Bird class may inherit methods like eat() and sleep() from a parent Animal class, as birds are a type of animal.

     • Hierarchy Building:

       • Inheritance allows for the creation of a hierarchy of classes, mirroring real-world relationships.
       • It simulates how objects relate to each other through an IS A relationship.

     • Understanding IS A Relationship:

       • The goal of inheritance is not just to inherit methods but to adhere to the IS A relationship rule.
       • It ensures that subclasses represent specialized versions of their superclass and are related in a meaningful way.

     • Avoiding Poor Design:

       • Inheritance should not be used indiscriminately for method reuse.
       • For example, a Bird class should not inherit from a Vehicle class solely to use the move() method. This violates the IS A relationship principle and leads to poor design.

     • Key Principle:

       • The IS A relationship is crucial for forming class hierarchies and ensuring proper code reuse where it makes sense.
       • Well-designed applications leverage inheritance to promote code reuse in a meaningful and logical manner.

4. Public vs. Private Methods/Properties:

   • Public methods and properties are accessible from external classes, while private methods and properties are only accessible within the class itself.
   • Private members cannot be inherited by child classes.
   • Inner nested classes within the same class definition have access to private members.

5. Class Constructor:

   • A constructor is a method used to instantiate an instance of a class.
   • It typically has the same name as the class and initializes specific properties.
   • Overloaded constructors allow for multiple constructor definitions with different parameters.

6. Overloaded Methods:

   • Overloaded methods have the same name but a different set of parameters.
   • The order of parameters matters, and parameters must have different data types to avoid compilation errors.

7. Abstract Class:

   • An abstract class cannot be instantiated but can be inherited.
   • It contains abstract methods that must be implemented by its child classes.
   • Abstract methods are declared without implementation and must be implemented by subclasses.

8. Instantiation:

   • Instantiation refers to the creation of an instance (object) of a class.
   • It occurs when the class constructor method is called, providing the object with properties and methods defined in the class blueprint.

9. Passing Parameters:

   • Passing parameters by value allows methods to access only the parameter's value, not the variable itself.
   • Passing parameters by reference passes a pointer to the variable, allowing methods to modify the original variable.

10. Method Overriding:

    • Method overriding occurs when a subclass provides its own implementation for a method inherited from a superclass.
    • It allows for customizing the behavior of inherited methods in child classes.

11. Exception Handling:

    • Exception handling is a process used to handle errors that occur during program execution.
    • It allows for graceful error handling, preventing the application from crashing and providing users with feedback on how to proceed.

12. "this" Object:

    • The "this" reference refers to the current instance of the object within a class.
    • It is used to access instance variables and methods within the class.

13. Pointer:

    • Pointers reference the memory location of a value in programming languages like C++.
    • They allow for direct manipulation of memory values, affecting the original data.

14. Static Methods:

    • Static methods exist independently of class instances and do not have access to instance variables.
    • They are useful for defining utility functions that do not require access to instance-specific data.

When to use functional vs object oriented solutiosn?

Functions are action based, and classes are state based

functions easier to write unit tests 

object oriented solution is better for real world simulation 

dunder methods