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Top 20 PHP Interview Questions for 2020



Last updated 10/06/2021

Top 20 PHP Interview Questions for 2020

What stands first when it comes to Web Development Language?

Of course, it’s PHP!

PHP is a popular general-purpose scripting language that is specially designed for Web Development purposes. Originally created by Rasmus Lerdorf in 1994,  PHP reference implementation is now produced by The PHP Group. 

Why is PHP so special you may ask? 

Well, along with executing any type of data including binary data, HTML data, PHP holds the existence of Various web template systems, web content management systems, and web frameworks that can be employed to orchestrate or facilitate the generation of that response. Hence, the web development world can never think of a step forward without PHP nowadays.

You already understand now that PHP skill is a basic need when it comes to web development. Right? We are well aware of it, and that’s why here comes the top 20 PHP interview questions that have been asked in most of the PHP interviews in 2020. Let us walk you through it!

1. What’s the difference between the include() and require () functions?

Both include() and require() function demands a specific file to work on. But on require() function the process exits with a lethal error if the file can’t be included. On the other hand, include() statement passes through and jumps to the next step in the execution.

2. How can we get the IP address of the client?

The $_SERVER["REMOTE_ADDR"] command helps us to get to the IP address of the client.

3. What’s the difference between unset() and unlink()

unset() is used for setting a variable to “undefined”. On the other hand, unlink() is used to delete a file being passed to it from the file system.

4. How do the main error types in PHP differ?


5. What is the difference between GET and POST?


6. How can you enable error reporting in PHP?

First, you need to check if “display_errors” is equal “on” in the php.ini or declare “ini_set('display_errors', 1)” in your script.

After that, include “error_reporting(E_ALL)” in your code to display all types of error messages during the script execution.

7. What are Traits?

Traits are a mechanism that allows you to create reusable code in languages like PHP that does not support multiple inheritances. A Trait cannot be instantiated on its own.

8. Can the value of a constant be changed during the script’s execution?

If the value of a constant is declared, it can’t be changed during the script’s execution.

9. Can you extend a Final defined class?

 A Final class or method declaration works towards preventing child class or method overriding. Hence it can’t be extended.

10. What are the __construct() and __destruct() methods in a PHP class?

(Question provided by Agli Pançi)

The Constructor method helps in initializing class properties and is called immediately after a new instance of the class is being created. 

The Destructor method doesn’t take any parameters.

11. How we can get the number of elements in an array?

The count() function helps to return the number of elements in an array.

12. What are the 3 scope levels available in PHP and how would you define them?

The 3 scope levels available in PHP are:

  • Private –  It is visible only in its own class
  • Public – It is visible to any other code accessing the class
  • Protected – This one is visible only to classes, parent(s) and classes that extend the current class

13. How can you execute PHP script from the command line?

 PHP command can be used in the command line to execute a PHP script. For example, A PHP file named test.php will use the following command to run the script from the command line.

php test.php

14. What is meant by variable variables in PHP?

If the value of a variable is being used as the name of any other variable,  it is called variable variables. We use $$ to declare variable variables in PHP.

15. How many types of arrays are there in PHP?

There are 3 types of arrays in PHP:

  • Numeric arrays 
  • Associative arrays
  • Multidimensional arrays.

16. Which function can be used to exit from the script after displaying the error message?

 exit() or die() function is used to exit from the current script after displaying the error message.

17. Which function is used in PHP to check the data type of any variable?

You can use gettype() function to check the data type of any variable.

18. How can you increase the maximum execution time of a script in PHP?

To increase the maximum execution time of a script, you have to change the value of the max_execution_time directive in the php.ini file.

19. How can you make a connection with MySQL server using PHP?

To make a connection with MySQL server, you have to provide MySQL hostname, username, and password to make a connection with the MySQL server in mysqli_connect() method or declaring database object of the mysqli class.

20. How can you retrieve data from the MySQL database using PHP?

Answer: Few functions to retrieve the data from the MySQL database using PHP are mentioned below:

  • mysqli_fetch_array() – Used to fetch the records as a numeric array or an associative array.
  • mysqli_fetch_row() – Used for fetching the records in a numeric array.
  • mysqli_fetch_assoc() – Used to fetch the records in an associative array.
  • mysqli_fetch_object() – Used to fetch the records as an object.



Apart from PHP Developers, PHP has become a priority for DevOps Engineers and Cloud engineers as well. Hence, once you possess a keen knowledge of PHP development, you can apply for these job profiles as well! The only thing you’ll be needing is a proper training regarding the same. And for that, we are here having your back! Check out our vast range of training programs, and pick up the one you’d like!

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