40+ PHP Interview Questions & Answers You Should Prepare in 2024

Coursesity Team -

Are you looking to prepare for a position as a PHP developer? Here are some of the most asked questions when interviewing for a position in PHP, strategically meant to test one's knowledge over beginner, intermediate, and advanced levels.

PHP is one of the really nice languages to learn for those starting their WordPress development or, in general, web development. It is pretty easy to learn. It becomes the backbone of dynamic web development.

To get further advanced in this field, there are a lot of free PHP tutorials online to learn from. Be it going to attend a PHP coding interview or some tips related to the technical interview in PHP; these questions will make you fully ready for it.

PHP Interview Questions for Beginners

1. Who is known as the father of PHP?

The father of PHP is Rasmus Lerdorf.

2. What was the old name of PHP?

The old name for PHP was "Personal Home Page Tools."

3. What is the difference between static and dynamic websites?

The static would load the same page for all of the users; on the other hand, the dynamic one can show custom pages following the interaction made for the users or other parameters set within the site.

4. What are the popular Content Management Systems (CMS) in PHP?

The general PHP-based Content Management Systems are WordPress, Joomla, Drupal, and Magento.

5. What is the difference between $message and message in PHP?

$message` is a regular variable, whereas `message is a variable variable. The value of $$message depends on the value of $message`.

6. What is PHP?

PHP is an Open Source server-side scripting language for dynamic pre-development of Web sites and it also can be inserted into HTML codes.

7. What does PHP stand for?

PHP stands for Hypertext Preprocessor.

8. What is the full form of PEAR?

PEAR means “PHP Extension and Application Repository.”

9. How do you execute a PHP script from the command line?

You can run the PHP script using the command:

  • php script.php

10. How do you run the interactive PHP shell from the command line interface?

You can start the interactive shell by using the following command:

  • php -a

11. Does PHP support multiple inheritance?

No, PHP only supports single inheritance, meaning a class can only extend one other class.

12. How does PHP compare objects?

PHP compares objects using == for comparing object values and === to check if two objects refer to the same instance.

Intermediate PHP Interview Questions

13. How can you embed PHP code in an HTML page?

You can embed PHP into an HTML page by using the <?php. ?> tags.

14. How does PHP interact with JavaScript?

PHP is server-side and JavaScript is client-side. These two interlink because both can communicate with one another through AJAX. As AJAX generates requests; server to browser, data will pass onto AJAX.

15. Name the different types of variables in PHP.

PHP supports various types of variables:

  • Integer
  • Float
  • String
  • Boolean
  • Array
  • Object

16. List the main types of errors in PHP and explain their differences.

  • Notice: Non-critical errors that do not stop script execution.
  • Warning: Serious errors, but the script continues running.
  • Fatal Error: Critical error that stops script execution.

17. What do we mean by ‘escaping to PHP’?

Escaping to PHP means embedding PHP code within an HTML file using PHP tags <?php ... ?> to execute server-side code.

18. How can JavaScript and PHP interact?

JavaScript can submit forms or use AJAX to pass data to PHP, and PHP can also create or compile or otherwise construct JavaScript code to be run on the client side in the browser.

19. How can a PHP script connect to a MySQL database?

Using the mysqli_connect() function:

  • $database = mysqli_connect("HOST", "USER_NAME", "PASSWORD");
  • mysqli_select_db($database, "DATABASE_NAME");

20. What is the difference between echo and print in PHP?

Both are the language constructs for output to the browser. echo can have more than one string and a print statement returns a value.

21. How can I display text via a PHP script?

You can display text using either echo or print.

Example:

  • echo "Hello, World!";

22. What is the use of the function func_num_args()?

The func_num_args( ) method returns the number or count of arguments passed to a function.

unlink( ) function removes the designation of a file from the filesystem.

24. Explain the use of mysql_pconnect().

mysql_pconnect() opens a persistent connection to the database. Once opened, it doesn't close even when the script has already been executed. It is deprecated in PHP 7.0 onwards.

25. How can you handle errors in PHP?

PHP handles errors using error handling functions like try, catch, and finally blocks, or setting custom error handlers with set_error_handler().

Advanced PHP Interview Questions

26. What is the use of the function imagetypes()?

The imagetypes() function returns the bit masks for the image types selected/ supported by PHP installation.

27. What is needed to use the image function in PHP?

Whether you use image functions or not depends on your system having the GD library installed and enabled.

28. What is the primary difference between include_once() and include()?

include_once() includes the file only once. If include_once() is called again for the same file in the same session, it won't include the file. include() does no checking.

29. How do you export data into an Excel file using PHP?

There is an ability to export data into Excel using the library PHPSpreadsheet or PHPExcel.

30. What is the major difference between ASP.NET AND PHP?

PHP- opens source server-side scripting language and ASP.Net is a web application framework brought up by Microsoft.

31. What is the use of sessions and cookies in PHP?

The session keeps the temporary data on the server whereas cookies store data in user browsers.

32. What is overloading and overriding in PHP?

  • Overloading: Dynamically creating properties and methods via magic methods.
  • Overriding: A subclass provides its implementation of a method inherited from the parent class.

33. What is the use of callbacks in PHP?

Callback: A function that is passed as an argument to another function.

34. In PHP, what is a lambda function?

The lambda function is anonymous, meaning it has no name. Hence, a variable or callback can be assigned to a function.

35. What are PHP Magic Methods/Functions?

Magic Methods in PHP are special methods that start with double underscores and therefore look something like __construct(), __destruct(), __get(), __set().

36. Explain PHP error handling.

PHP provides error-handling mechanisms through custom error handlers, try-catch blocks, and functions like set_error_handler().

37. What is the use of include_once()?

include_once() includes a file if it has not been included before in the script otherwise it is not repeated; it includes the file and allows the inclusion of files only once.

38. How can you optimize PHP performance?

The basic optimization of PHP can be enabled with caching such as APC or Memcached among many others, reducing database queries, and applying efficient algorithms.

39. How do you prevent SQL injection in PHP?

In preventing SQL injection in PHP, prepared statements with bounded parameters are used instead of PDO, MySQLi, etc.

40. What is the purpose of the Composer tool in PHP?

Composer handles in PHP all the dependency needs of a user he wants to add to his project as libraries and other packages.

41. How do you handle file uploads in PHP?

The superglobal that manages the uploading of the file is the superglobal $FILES, and to move this file into a directory move_uploaded_file() is a function.

Tips for a PHP Interview

  • Be ready to code: The candidate will be expected to either actually write code on the spot or solve some problems on a whiteboard.
  • SQL and databases: PHP developers are very often working with databases. Understand SQL appropriately.
  • PHP frameworks: Knowledge of big PHP frameworks-Laravel or Symfony-is going to turn out an advantage.
  • Security: The most common security weaknesses when operating with PHP-like SQL injection, XSS, and CSRF-and how not to fall into these traps.

Conclusion

Preparation for an interview for the position of a PHP developer using the set of questions above will make you confident and well-armed. Be it a technical PHP interview, coding PHP interview, or even PHP interview questions if you are an experienced developer, these questions touch on important areas you are likely to come across.

People are also reading: