Are you a PHP beginner eager to master Object-Oriented Programming (OOP) and prepare for interviews? Look no further! Our blog features 30 essential PHP OOPs Interview Questions and Answers for Beginners that cover all the key concepts you need to know.
From understanding classes, objects, and methods to delving into inheritance, encapsulation, and polymorphism, each question is tailored for beginners and explained in simple terms. These most-asked questions are perfect for building your confidence and sharpening your PHP skills.
Must Read:- Best 30 Advanced PHP OOPs Interview Questions and Answers
Mostly Asked PHP OOPs Interview Questions and Answers
Q1. What is PHP language?
Ans: Server-side scripting language that helps developers create dynamic web pages. Its main goal is to build web servers that can retrieve data from forms, create web pages, send and receive cookies, etc. Some of the big giants, like Facebook, Lyft, Drupal, etc., need it many of them PHP developers
Q2. What are the advantages of using PHP language?
Ans: The advantages of using PHP are as follows:
- Easy Maintenance
- Open Source platform
- Highly Flexible and adaptable
- Simple to learn
- Scalable
- Efficient
Q3. What is a subclass?
Ans: The subclass is a part of Inheritance. The subclass is an entity, which inherits from another class. It is also known as the child class.
Q4. What do you mean by object-oriented programming?
Ans: Object-oriented programming (OOP) is a computer programming model that organizes software design around objects, or data rather than logic and functions. In OOP, objects are data fields with unique properties and behavior
Q5. What do you mean by Inheritance?
Ans: Property is a key concept in Object-Oriented Programming of PHP that allows a class (child) to inherit properties and methods from another class (parent) using extends keyword This facilitates code reuse and simplifies maintenance by the shared functionality that enables it. The child class can access the publicly wrapped members of the parent class and add its own property or override methods to extend the implementation. However, private members of the parent group are not directly accessible by the child group.
Q6. Explain the types of access modifiers in PHP?
Ans:
- Public: Members declared as public are accessible from anywhere—both inside and outside the class.
- Protected: Members declared as protected can only be accessed within the class itself and by subclasses that extend the class.
- Private: Members declared as private are restricted to the class where they are defined and cannot be accessed outside of it, even by subclasses.
This version maintains the original meaning while enhancing structure and readability.
Q7. What are some of the main Object Oriented Programming languages?
Ans: Programming languages that adhere to the Object-Oriented Programming (OOP) paradigm are referred to as Object-Oriented Programming languages. Some of the most widely used OOP languages include: This version makes the sentence more concise and professional while retaining its original meaning.
- Java
- C++
- Javascript
- Python
- PHP
- And many more.
Q8. What is a PHP session?
Ans: PHP sessions can be used to store data or information on a number of web pages in an Internet browser that are not stored in individual computer memory A PHP session can be started using the session_start() method, and the session factor is started world with the $_SESSION all changes.
Q9. What is the difference between echo and print?
| echo | |
| echo can take multiple arguments | print can only take one argument, so it can be used in expressions. |
| echo does not return a value, | print returns 1. This means print can be used in expressions, but echo cannot |
| echo is generally faster than print | Slower than echo |
Q10. What are the popular Content Management Systems (CMS) in PHP?
Ans: Some popular PHP-based CMS platforms are:
- WordPress: Known for ease of use and extensive plugin support.
- Drupal: Ideal for complex, scalable websites.
- Joomla: Flexible and user-friendly for medium-sized sites.
- Magento: Specialized for e-commerce websites.
Q11. What are the popular frameworks in PHP?
Ans:
Q12. What is the difference between Structured Programming and Object-Oriented Programming?
| Object-Oriented Programming (OOP) | Structural Programming |
| Built around objects that encapsulate both state and behavior. | Organizes programs into functions and procedures for logical structure. |
| Follows a bottom-to-top approach. | Follows a top-to-bottom approach. |
| Restricts the flow of data to authoriz parts, ensuring better security. | No restrictions on data flow; data can accessed anywhere. |
| Features like inheritance and polymorphism enhance code reusability. | Code reusability is achieved through functions and loops. |
| Easier to modify and update code due to encapsulation and abstraction. | Modifying and maintaining code is more challenging. |
Q13. What are the different types of Polymorphism?
Ans: Polymorphism in programming can be broadly classified into two types based on the point in time when the call to an object or function is resolved. These types determine how and when the appropriate method or function to execute is chosen during the program’s execution. The two classifications are as follows:
A) Compile-Time Polymorphism
Compile-time polymorphism, also known as static polymorphism or initial binding, is a type of polymorphism that is used to bind that code at compile time A method overload or operator overload is an example of a compile-time polymorphism.
B) Runtime Polymorphism
Also known as dynamic polymorphism or delayed binding, runtime polymorphism is a type of polymorphism in which a task is specified to be actually executed at runtime or during execution Method control is an example of this method.
Q14. What is a constructor in PHP?
Ans: A constructor is a special method called when an object is instantiated. It initializes the object’s properties. It’s defined using the __construct() method.
class Car {
public $brand;
public function __construct($brand) {
$this->brand = $brand;
}
}
$myCar = new Car("Honda");
echo $myCar->brand; // Output: HondaQ15. What is an abstract class in PHP?
Ans: An abstract class is a blueprint that cannot be instantiated on its own. It is intended to be extended by other classes. Abstract classes can include abstract methods—methods without implementation—that must be defined in the subclasses that inherit them.
Q16. What is the difference between “==” and “===” in PHP?
Ans:
“==” checks if the values are equal, performing type coercion if necessary
“===” checks if the values and types are the same, without performing type coercion.
Q17. What are magic methods in PHP?
Ans: Magic methods in PHP are special predefined methods that get triggered automatically when specific operations are performed on an object. These methods handle actions like object creation, destruction, and property access dynamically. Common examples include __construct() for initializing objects, __destruct() for cleanup, __call() for handling undefined methods, and __get()/__set() for managing inaccessible properties. Magic methods enhance PHP’s flexibility and dynamic behavior.
Q18. What are the types of errors in PHP?
Ans: There are several types of errors in PHP:
- Parse errors: Occur when PHP cannot understand the code structure.
- Fatal errors: Occur when PHP cannot execute a script due to critical issues.
- Warning errors: Non-critical errors that allow the script to continue running.
- Notice errors: Minor issues, usually indicating potential bugs or code improvements.
Q19. What is the difference between GET and POST methods in PHP?
Ans:
- GET sends data through the URL (limited size), visible to users, and can be cached.
- POST sends data via HTTP headers, is not visible to users, and is more secure than GET. It is often used for submitting sensitive data.
Q20. What is an array in PHP?
Ans: An array is a variable that can hold multiple values in a single variable. PHP supports both indexed arrays (with numeric keys) and associative arrays (with named keys).
Q21. Difference between Cookies and Session ?
Ans :
| Session | Cookies |
| A session stores the variables and their values within a file in a tempora directory on the server. | Cookies are stored on the user’s computer as a text file. |
| The session ends when the user logout from the application or closes his web browser. | Cookies end on the lifetime set by the user. |
| It can store an unlimited amount of data. | It can store only limited data. |
| We can store as much data as we want within a session, but there is a maximum memory limit, which a script can use at one time, and it is 128 MB. | The maximum size of the browser’s cookies is 4 KB. |
| We need to call the session_start() function to start the session. | We don’t need to call a function to start a cookie as it is stored within the local computer. |
Q 22. What are the differences between include, require, include_once, and require_once?
Ans:
- include: Includes a file; throws a warning if the file is miss
- require: Includes a file; throws a fatal error if the file is miss
- include_once: Includes a file only once; prevents re-inclusio
- require_once: Same as include_once, but throws a fatal error if the file missing.
Q 23. What is the difference between isset() and empty()?
Ans:
- isset(): Checks if a variable is defined and not nul
- empty(): Checks if a variable is undefined, null, or evaluates to false.
Q 24. How do you handle file uploads in PHP?
Ans: Use the $_FILES superglobal to handle uploaded files and move them using move_uploaded_file().
Q25. What is composer in PHP?
Ans: Composer is a dependency manager for PHP, used to install libraries and manage autoloading.
Q 26. What is the name of scripting engine in PHP?
Ans: The scripting engine that powers PHP is called Zend Engine 2.
Q27. What are the different loops in PHP?
Ans: For, while, do-while and for each.
Q28. How many types of array are there in PHP?
Ans: There are three types of array in PHP:
- Indexed array: an array with a numeric key.
- Associative array: an array where each key has its specific values.
- Multidimensional array: an array containing one or more arrays within itself.
Q29. What is PHP session_start() and session_destroy() function?
Ans: PHP session_start() function is used to start the session. It starts new or resumes the current session. It returns the current session if the session is created already. If the session is not available, it creates and returns new sessions.
Q30. Difference between Primary and Foreign Key?
Ans: The primary key is a unique identifier within its table, whereas a foreign key is a reference in one table to a primary key in another.
Primary keys enforce uniqueness within their table, ensuring each record is identifiable. Foreign keys, however, are used to establish and navigate relationships between tables.
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