Top 30 Most Common Php Viva Questions You Should Prepare For
Written by
James Miller, Career Coach
Interviewing for a PHP development role can feel daunting, especially when faced with technical viva questions. These oral examinations are designed to probe your depth of knowledge, practical experience, and problem-solving skills in real time. Unlike written tests, viva questions require you to articulate your understanding clearly and concisely, often under pressure. Preparing thoroughly for the most common php viva questions is crucial not only for demonstrating your technical prowess but also for building confidence. This guide breaks down what these questions entail, why interviewers ask them, and provides structured, answer-ready responses for 30 frequently asked topics. By mastering these, you'll be well on your way to acing your next PHP interview and securing your desired position. Understanding the nuances of PHP fundamentals, object-oriented programming, database interactions, security, and modern framework concepts is key. This article provides a targeted approach to help you focus your study and practice your responses, making the interview process smoother and more successful. Dive in and boost your readiness for those critical php viva questions.
What Are php viva questions?
PHP viva questions are verbal technical questions asked during an interview process for roles involving PHP development. "Viva" is short for "viva voce," which means "by word of mouth." These questions cover a range of topics, from core PHP syntax and functions to object-oriented programming, database interaction, security best practices, error handling, performance optimization, and knowledge of frameworks like Laravel or Symfony. They aim to assess not just what you know, but how well you can explain it and apply it to practical scenarios. Unlike coding tests which evaluate your ability to write code, viva questions test your theoretical foundation and ability to articulate complex concepts clearly. They often start with fundamental questions and progress to more complex or scenario-based queries depending on the level of the position. Being prepared for common php viva questions allows you to showcase your understanding and communicate your technical thinking process effectively to the interviewer.
Why Do Interviewers Ask php viva questions?
Interviewers ask php viva questions for several key reasons. Firstly, they assess your foundational knowledge and understanding of core PHP concepts. Can you explain why certain functions are used or how different language constructs work? Secondly, viva questions reveal your ability to think on your feet and articulate technical ideas clearly. This is crucial for collaboration within a team and explaining your work. Thirdly, they help gauge your practical experience and how you apply theoretical knowledge to real-world problems. Asking about handling errors, security, or performance shows if you've encountered common challenges. Fourthly, viva questions can explore your familiarity with advanced topics, design patterns, or specific frameworks relevant to the role, distinguishing candidates based on their depth of expertise. Finally, they provide insight into your communication skills and confidence when discussing technical subjects. Effectively answering php viva questions demonstrates competence and readiness for the role.
Preview List
What is PHP?
What is the difference between GET and POST methods in PHP?
What are PHP sessions and cookies?
What is the difference between echo and print in PHP?
What is PEAR in PHP?
What are PHP magic methods/functions?
What are the different types of PHP variables?
How do you set an infinite execution time for a PHP script?
What are the different types of arrays in PHP?
How does the ‘foreach’ loop work in PHP?
What are constructor and destructor in PHP?
What is the difference between require and include?
What is the PHP scripting engine called?
What is the difference between PHP4 and PHP5?
Is PHP a case-sensitive language?
What are some popular PHP frameworks?
What are some popular PHP Content Management Systems (CMS)?
What is Memcache and Memcached in PHP?
How do you manage large-scale PHP applications?
What design patterns have you used in your PHP projects?
How do you handle database migrations in PHP projects?
What is your approach to writing unit tests in PHP?
What tools do you use for debugging PHP code?
What is CSRF and how do you prevent it?
Explain type hinting in PHP.
What is middleware in Laravel?
What is the difference between Laravel and Symfony?
Explain the Repository Pattern in PHP.
What are PHP traits?
How do you optimize PHP code for performance?
1. What is PHP?
Why you might get asked this:
This is a fundamental question to check if you know the basics of the language you're applying for. It verifies your understanding of PHP's purpose and environment.
How to answer:
Define the acronym, describe its primary use case (server-side scripting for web), and mention its popularity or key features like being open-source.
Example answer:
PHP stands for Hypertext Preprocessor. It's a widely-used open-source server-side scripting language designed for web development. It's embedded within HTML and used to create dynamic web content and interact with databases.
2. What is the difference between GET and POST methods in PHP?
Why you might get asked this:
This tests your understanding of fundamental HTTP request methods used in web forms and data submission. It's critical for handling user input securely and correctly.
How to answer:
Explain how data is sent for each method (URL vs. HTTP body) and highlight key differences like visibility, security implications, and data size limits.
Example answer:
GET sends data appended to the URL, making it visible and less secure, suitable for non-sensitive data and linking. POST sends data in the HTTP request body, making it invisible in the URL, more secure, and suitable for sensitive or large data.
3. What are PHP sessions and cookies?
Why you might get asked this:
This assesses your knowledge of managing state in stateless web applications, crucial for user authentication, shopping carts, and personalized experiences.
How to answer:
Define each, explain where data is stored (server vs. client), and mention their typical use cases and security considerations.
Example answer:
Sessions store data on the server, identified by a session ID usually stored in a cookie. They are more secure for sensitive data. Cookies store small amounts of data directly on the client's browser, used for things like remembering user preferences or login status.
4. What is the difference between echo and print in PHP?
Why you might get asked this:
A common beginner question to verify basic output function knowledge. It checks attention to detail regarding language constructs.
How to answer:
Explain their primary function (outputting strings) and highlight the technical differences regarding return values and arguments.
Example answer:
Both echo and print are used to output strings. The main differences are that echo is slightly faster as it doesn't return a value and can take multiple arguments, while print returns 1 and can only take one argument.
5. What is PEAR in PHP?
Why you might get asked this:
This tests your awareness of the PHP ecosystem and resources available for developers to reuse code and manage dependencies.
How to answer:
Define the acronym (PHP Extension and Application Repository) and describe its purpose as a framework for reusable PHP components and dependency management.
Example answer:
PEAR stands for PHP Extension and Application Repository. It's a framework and distribution system for reusable PHP components. It provides a standardized way to manage and install libraries and extensions.
6. What are PHP magic methods/functions?
Why you might get asked this:
This probes your understanding of PHP's object-oriented features, specifically how objects interact with the language's core functionalities automatically.
How to answer:
Explain that they are special methods automatically called by PHP in response to certain actions (e.g., object creation, destruction, serialization), usually starting with __.
Example answer:
Magic methods are special functions in PHP classes that are automatically triggered upon certain events. Examples include construct() for object creation, destruct() for object destruction, get() and set() for accessing object properties.
7. What are the different types of PHP variables?
Why you might get asked this:
Tests fundamental knowledge of PHP's data types, essential for understanding how data is stored and manipulated.
How to answer:
List and briefly describe the scalar types (boolean, integer, float/double, string) and compound types (array, object), and special types (resource, NULL).
Example answer:
PHP has several data types: Scalar types include Boolean, Integer, Float (or Double), and String. Compound types are Array and Object. Special types are Resource (e.g., database connections) and NULL.
8. How do you set an infinite execution time for a PHP script?
Why you might get asked this:
This assesses your ability to control script execution environment settings, useful for long-running processes like imports or cron jobs.
How to answer:
Mention the settimelimit() function and the specific argument value needed for infinite execution.
Example answer:
You can set an infinite execution time for a PHP script by using the settimelimit() function and passing 0 as the argument, like settimelimit(0);. This overrides the default maxexecutiontime setting in php.ini.
9. What are the different types of arrays in PHP?
Why you might get asked this:
Evaluates your understanding of PHP's versatile array structure, a cornerstone data type for lists and maps.
How to answer:
Describe the two main types: indexed (numeric keys) and associative (string keys), explaining how elements are accessed in each.
Example answer:
PHP supports two main types of arrays: Indexed arrays use sequential integer keys (0, 1, 2...). Associative arrays use named string keys. A single PHP array can contain a mix of both key types.
10. How does the ‘foreach’ loop work in PHP?
Why you might get asked this:
Checks your knowledge of iterating over collections, a very common task in PHP development.
How to answer:
Explain its primary use for iterating over arrays and objects. Describe the two syntax variations: iterating over values only and iterating over key-value pairs.
Example answer:
The foreach loop is specifically designed for iterating over arrays and objects. It provides a simple way to loop through each element. You can iterate through just the values (foreach ($array as $value)) or through both keys and values (foreach ($array as $key => $value)).
11. What are constructor and destructor in PHP?
Why you might get asked this:
Tests your understanding of object lifecycle management in OOP PHP, fundamental for resource initialization and cleanup.
How to answer:
Define construct() as the method called when an object is created and destruct() as the method called when an object is destroyed or goes out of scope.
Example answer:
The constructor (construct()) is a magic method called automatically when a new object is created. It's typically used for initializing object properties. The destructor (destruct()) is called when the object is destroyed or the script ends, often used for cleanup like closing database connections.
12. What is the difference between require and include?
Why you might get asked this:
A classic question assessing your knowledge of file inclusion methods and their behavior on encountering errors.
How to answer:
Explain that both include external files, but differentiate their error handling: require causes a fatal error and stops execution if the file is missing, while include raises a warning and continues execution.
Example answer:
Both require and include are used to insert code from one PHP file into another. The key difference is error handling: require will produce a fatal error (ECOMPILEERROR) and halt the script if the file is not found, whereas include will produce a warning (E_WARNING) but the script will continue to run.
13. What is the PHP scripting engine called?
Why you might get asked this:
Tests your awareness of the core technology that powers PHP execution.
How to answer:
State that the primary engine is the Zend Engine.
Example answer:
The primary scripting engine used by PHP is the Zend Engine. It's responsible for compiling and executing the PHP code at runtime.
14. What is the difference between PHP4 and PHP5?
Why you might get asked this:
Historical context question, showing awareness of PHP's evolution, particularly the significant shift towards modern OOP in PHP5.
How to answer:
Highlight the major change: PHP5 introduced a significantly improved object model and full support for OOP compared to the more limited support in PHP4. Mention the different Zend Engines.
Example answer:
PHP5 was a major overhaul from PHP4, primarily introducing a significantly improved and fully featured object-oriented programming model (with features like public/private/protected, interfaces, abstract classes, magic methods) using Zend Engine 2. PHP4 used Zend Engine 1 and had limited OOP support.
15. Is PHP a case-sensitive language?
Why you might get asked this:
Checks your understanding of language syntax rules, important for avoiding common coding errors.
How to answer:
Explain that PHP is partially case-sensitive: variable names are case-sensitive, but function names, class names, and keywords are generally case-insensitive.
Example answer:
PHP is partially case-sensitive. Variable names are case-sensitive (e.g., $myVar is different from $myvar), but function names, class names, and language keywords (like if, else, echo) are case-insensitive.
16. What are some popular PHP frameworks?
Why you might get asked this:
Assesses your familiarity with modern PHP development practices and tools used to build scalable and maintainable applications.
How to answer:
List several widely recognized and used PHP frameworks.
Example answer:
Some popular PHP frameworks include Laravel, Symfony, CodeIgniter, CakePHP, and Yii. Frameworks provide structure, libraries, and best practices to speed up development and improve code quality.
17. What are some popular PHP Content Management Systems (CMS)?
Why you might get asked this:
Tests your knowledge of common platforms built with PHP, relevant for web development roles that might involve CMS customization or integration.
How to answer:
List several well-known CMS platforms built on PHP.
Example answer:
Popular PHP Content Management Systems include WordPress, Joomla, Drupal, and Magento (for e-commerce). These platforms are widely used for building websites and applications.
18. What is Memcache and Memcached in PHP?
Why you might get asked this:
Probes your understanding of caching technologies used to improve application performance by reducing database load.
How to answer:
Explain that they are in-memory caching systems. Differentiate between the original Memcache (extension) and the more modern Memcached (daemon + extension).
Example answer:
Memcache and Memcached are distributed memory caching systems. They store data in RAM to speed up data retrieval. Memcache is an older PHP extension; Memcached is a newer, more powerful system consisting of a daemon and a PHP extension to interact with it.
19. How do you manage large-scale PHP applications?
Why you might get asked this:
Evaluates your experience and approach to building and maintaining complex, high-traffic applications, showing architectural thinking.
How to answer:
Discuss using frameworks, adopting design patterns (like MVC), modular design, code organization, version control, automated testing, and potentially microservices or scaling techniques.
Example answer:
Managing large-scale PHP applications involves using robust frameworks for structure, adopting design patterns like MVC, ensuring modular code organization, implementing strong version control, utilizing automated testing, optimizing database interactions, and considering caching and horizontal scaling.
20. What design patterns have you used in your PHP projects?
Why you might get asked this:
Tests your knowledge of common software design solutions and your ability to apply structured approaches to problem-solving.
How to answer:
Mention specific patterns you are familiar with or have implemented, such as Singleton, Factory, MVC, or Dependency Injection, and briefly explain their context.
Example answer:
I commonly use patterns like MVC (Model-View-Controller) in framework-based projects. I've also applied the Singleton pattern for database connections, Factory patterns for object creation, and Dependency Injection for managing class dependencies, improving testability and modularity.
21. How do you handle database migrations in PHP projects?
Why you might get asked this:
Checks your process for managing database schema changes over time, essential for team development and deployment.
How to answer:
Explain the concept of migrations (version-controlling database schema) and mention tools or framework features used for this, like Laravel's Artisan migrate command or similar tools.
Example answer:
I handle database migrations by using migration tools provided by frameworks, like Laravel's Artisan commands. This allows me to define database schema changes in version-controlled files, ensuring consistency across environments and simplifying team collaboration and deployment.
22. What is your approach to writing unit tests in PHP?
Why you might get asked this:
Assesses your commitment to code quality, reliability, and maintainability through automated testing practices.
How to answer:
Mention using a testing framework like PHPUnit. Describe the process: testing individual components in isolation, mocking dependencies, and aiming for good code coverage.
Example answer:
My approach involves using PHPUnit to write automated unit tests for individual classes and methods. I focus on testing units in isolation, using mocks or stubs for dependencies to ensure tests are fast, reliable, and accurately reflect the component's behavior.
23. What tools do you use for debugging PHP code?
Why you might get asked this:
Tests your practical skills in identifying and resolving issues in code.
How to answer:
Mention basic debugging functions (vardump, printr) for quick checks and more advanced tools like Xdebug integrated with an IDE for step-through debugging.
Example answer:
For quick checks, I use functions like vardump() or printr(). For more complex debugging, I rely on Xdebug integrated with an IDE like PHPStorm, which allows setting breakpoints, stepping through code execution, and inspecting variables interactively.
24. What is CSRF and how do you prevent it?
Why you might get asked this:
Evaluates your understanding of common web security vulnerabilities and how to mitigate them.
How to answer:
Define CSRF (Cross-Site Request Forgery) as forcing a user to execute unwanted actions. Explain prevention methods, primarily using CSRF tokens and potentially SameSite cookies.
Example answer:
CSRF, or Cross-Site Request Forgery, is an attack where a malicious site tricks a user's browser into performing an unwanted action on another site where they are authenticated. It's prevented by using unique, unpredictable CSRF tokens with forms, verifying them on the server side, and using SameSite cookie attributes.
25. Explain type hinting in PHP.
Why you might get asked this:
Tests your knowledge of modern PHP features that improve code robustness and readability.
How to answer:
Explain that type hinting (or type declarations) allows specifying the expected data type for function arguments, return values, and class properties, enabling PHP to enforce types and catch errors early.
Example answer:
Type hinting allows developers to declare the expected data type for function parameters, function return values, and class properties. This improves code readability, helps static analysis tools, and allows PHP to throw TypeError exceptions if the type doesn't match, catching bugs earlier.
26. What is middleware in Laravel?
Why you might get asked this:
Specific to Laravel development, this tests your understanding of how request processing is handled in the framework.
How to answer:
Describe middleware as layers that filter or process HTTP requests before they reach the application's core logic (like controllers) or after they leave it. Give examples like authentication or CORS handling.
Example answer:
In Laravel, middleware provides a convenient mechanism for filtering HTTP requests entering your application. It acts as a layer between the request and your application logic, handling tasks like authentication, CORS headers, logging, or request validation before the request reaches a route or controller.
27. What is the difference between Laravel and Symfony?
Why you might get asked this:
Compares two leading PHP frameworks, assessing your awareness of the ecosystem and ability to discuss framework choices.
How to answer:
Highlight their relationship (Laravel is built on Symfony components). Discuss common perceptions: Laravel is often seen as faster for rapid development and more opinionated, while Symfony is viewed as more flexible, stable, and suitable for complex, long-term enterprise projects.
Example answer:
Laravel is built upon many Symfony components. Laravel is often preferred for rapid application development due to its many built-in features and ease of use. Symfony is considered more flexible and stable, often chosen for complex enterprise-level applications, and is seen as a set of building blocks.
28. Explain the Repository Pattern in PHP.
Why you might get asked this:
Tests your knowledge of architectural patterns used to decouple application logic from data access code.
How to answer:
Describe it as an abstraction layer between the data access layer and the business logic. Repositories encapsulate the logic required to retrieve data sources, acting as collections of domain objects.
Example answer:
The Repository Pattern provides an abstraction layer for the data access layer. It centralizes data access logic, presenting a collection-like interface to the domain or business logic. This decouples the application from the specific data source technology, making the code more testable and maintainable.
29. What are PHP traits?
Why you might get asked this:
Tests your knowledge of PHP's mechanism for code reusability in single-inheritance languages, introduced in PHP 5.4.
How to answer:
Explain that traits are a mechanism for code reuse in single inheritance languages. They allow a class to use methods and properties from one or more traits without traditional inheritance.
Example answer:
Traits are a feature in PHP that enables code reuse by allowing classes to inherit methods and properties from multiple sources, overcoming the limitations of single inheritance. They are used with the use keyword within a class.
30. How do you optimize PHP code for performance?
Why you might get asked this:
Evaluates your practical skills in making applications faster and more efficient, a critical aspect of professional development.
How to answer:
Suggest several techniques: database query optimization, caching (opcode, data), minimizing external requests, efficient loop usage, using optimized PHP functions, and profiling code to identify bottlenecks.
Example answer:
Optimization involves several techniques: optimizing database queries and using appropriate indexes, implementing various caching strategies (opcode caching like Opcache, data caching with Memcached/Redis), minimizing I/O operations, using efficient built-in functions, profiling code to find bottlenecks, and keeping PHP and extensions updated.
Other Tips to Prepare for a php viva questions
Preparing for php viva questions goes beyond just memorizing answers. It requires a deep understanding of the concepts and the ability to articulate them clearly. "The difference between ordinary and extraordinary is that little extra," as Jimmy Johnson said. Practice explaining concepts out loud or to a friend. Use resources like online tutorials, official PHP documentation, and framework documentation to solidify your understanding. Consider using tools designed for interview preparation. The Verve AI Interview Copilot (https://vervecopilot.com) can simulate interview environments and provide feedback on your responses, helping you refine your explanations for php viva questions. It's invaluable for practicing articulation and confidence. Remember, interviewers are looking for clear communication as much as technical correctness. Don't be afraid to ask for clarification if you don't understand a question. A structured approach, combining knowledge acquisition with practice, will make you significantly more confident. Leverage tools like Verve AI Interview Copilot to get targeted practice on common php viva questions and specific technical areas. Stay calm, listen carefully, and take a moment to structure your answer before speaking. "By failing to prepare, you are preparing to fail," warned Benjamin Franklin, a sentiment that definitely applies to tackling challenging php viva questions.
Frequently Asked Questions
Q1: Should I memorize code examples for php viva questions?
A1: Focus on understanding concepts. Briefly mentioning syntax or common functions is good, but complex code is rarely required verbally.
Q2: How deep should my answers be for php viva questions?
A2: Aim for clear, concise answers that demonstrate understanding. Elaborate with practical examples if appropriate, but avoid excessive detail unless asked.
Q3: What if I don't know the answer to a php viva question?
A3: Be honest. State that you are not sure but perhaps mention related concepts or how you would approach finding the answer.
Q4: Are framework-specific php viva questions common?
A4: Yes, especially if the job description mentions a specific framework like Laravel or Symfony. Prepare based on the listed requirements.
Q5: How can I practice for php viva questions?
A5: Review core concepts, explain topics out loud, practice with a friend or mentor, and use interview preparation tools like Verve AI Interview Copilot.
Q6: Is it okay to ask clarifying questions during a technical viva?
A6: Absolutely. Asking for clarification shows you are engaged and want to provide the most relevant answer.
