Viva Vice on OOP in PHP
Q1. What is OOPS?
OOPS is abbreviated as Object Oriented Programming system in which programs are considered as a collection of objects. Each object is nothing but an instance of a class.
Q2. Write basic concepts of OOPS?
Q3. What is a class?
A class is simply a representation of a type of object. It is the blueprint/ plan/ template that describe the details of an object.
Q4. What is an object?
Object is termed as an instance of a class, and it has its own state, behavior and identity.
Q5. What is Encapsulation?
Wrapping up member variables and methods together into a single unit (i.e. Class) is called Encapsulation.
Q6. What is Polymorphism?
It is simply “One thing, can use in different forms”
or example, One car (class) can extend two classes (Honda & Hyundai)
Q7. . What is Inheritance?
Inheritance is a concept where one class shares the structure and behavior defined in another class.
Q8. Which version of PHP supports OOPs concepts?
Q9. Write the syntax of declaring Class in PHP?
class ClassName  
        // Class properties and methods   
Q10. Write the syntax Of declaring object in PHP?
$obj = new MyClass();
Q11. What Is Difference Between Class And Interface?
Interfaces do not contain business logic
You must extend interface to use.
You can’t create object of interface.
Q12. What Is Static Keyword In Php?
If we declare a Method or Class Property as static, then we can access that without use of instantiation of the class. Static Method are faster than Normal method.
Q13. What Is Object Iteration?
PHP provides a way for objects to be iterate through a list of items, for this we can use foreach. Only visible properties will be listed.
Q14. Difference between class and an object?
An object is an instance of a class. Objects hold any information , but classes don’t have any information. Definition of properties and functions can be done at class and can be used by the object.
Class can have sub-classes, and an object doesn’t have sub-objects.
Q15. What is the difference between structure and a class?
A structure is used for grouping data whereas class can be used for grouping data and methods. Structures are exclusively used for data and it doesn’t require strict validation , but classes are used to encapsulates and inherit data which requires strict validation.
Q16. What are the advantages of object oriented programming?
Code Reusability: it can be achieved through inheritance and traits.
Modularity: it can be achieved through breaking large code into small modules, Modularity reduces complexity.
Flexibility: it can be achieved through polymorphism.
Maintainability: it is to maintain code which follows Object Oriented Programming Concepts.
Security: it can be achieved through Encapsulation.
Testability: it is easy to test.


  1. Sebesta,”Concept of programming Language”, Pearson Edu
  2. Louden, “Programming Languages: Principles & Practices” , Cengage Learning
  3. Tucker, “Programming Languages: Principles and paradigms “, Tata McGraw –Hill.
  4. E Horowitz, “Programming Languages”, 2nd Edition, Addison Wesley