Getting a job on PHP? Take a look at these questions and try answering them!

1. 25 PHP Interview
Questions – Can You Answer
Them All?

2. Let’s take a look at some tips!

3. Tip 1
•“One of the most important things I watch out is the
creativity of the person I interview. I try to catch the
developers who are constantly learning new things, they are
driven by curiosity and also very creative, not just in problem
solving but in general too. I mostly ask about PHP and
PostgreSQL (I use this combo most of the time).” ~ Laszlo
Levente Mári, ex-Googler

4. Tip 2
•“During the interview of a potential candidate I am aiming to
understand how updated they are with the new language
features as well as their level of understanding of basic
operations. In my opinion, this will define how good a
developer will become in the future.” ~Agli Pançi, Lead
Developer

5. Tip 3
•“I would expect from a junior developer is that know the
basics of programing and how apply these basics to php. I
wouldn’t expect that a Junior Developer knows the name of
certain functions or complex terms on PHP.” ~Oscar Andrés
Monroy, Senior PHP Developer

6. Now, the interview questions…

7. Question #1
•What’s the difference between the include() and require()
functions?

8. Question #2
•How can we get the IP address of the client?

9. Question #3
•What’s the difference between unset() and unlink() ?

10. Question #4
•What is the output of the following code:
$a = '1';
$b = &$a;
$b = "2$b";
echo $a.", ".$b;

11. Question #5
•What are the main error types in PHP and how do they
differ?

12. Question #6
•What is the difference between GET and POST?

13. Question #7
•How can you enable error reporting in PHP?

14. Question #8
•What are Traits?

15. Question #9
•Can the value of a constant change during the script’s
execution?

16. Question #10
•Can you extend a Final defined class?

17. Question #11
•What are the __construct() and __destruct() methods in a PHP
class?

18. Question #12
•How we can get the number of elements in an array?

19. Question #13
•How would you declare a function that receives one
parameter name hello?

20. Question #14
•The value of the variable input is a string 1,2,3,4,5,6,7. How
would you get the sum of the integers contained inside input?

21. Question #15
•Suppose you receive a form submitted by a post to
subscribe to a newsletter. This form has only one field, an
input text field named email. How would you validate
whether the field is empty? Print a message "The email cannot
be empty." in this case.

22. Question #16
•Suppose that you have to implement a class named
Dragonball. This class must have an attribute named ballCount
(which starts from 0) and a method iFoundaBall. When iFoundaBall
is called, ballCount is increased by one. If the value of ballCount
is equal to seven, then the message “You can ask your wish.” is
printed, and ballCount is reset to 0. How would you
implement this class?

23. Question #17
•What are the 3 scope levels available in PHP and how
would you define them?

24. Question #18
•What are getters and setters and why are they important?

25. Question #19
•What does MVC stand for and what does each component
do?

26. Question #20
•How does one prevent the following Warning ‘Warning:
Cannot modify header information – headers already sent’
and why does it occur in the first place?

27. Question #21
•What are SQL Injections, how do you prevent them and
what are the best practices?

28. Question #22
•What does the following code output?
$i = 016;
echo $i / 2;

29. Question #23
•Why would you use === instead of ==?

30. Question #24
•What are PSRs? Choose 1 and briefly describe it.

31. Question #25
•What PSR Standards do you follow? Why would you follow
a PSR standard?

32. Question #26
•Do you use Composer? If yes, what benefits have you found
in it?

33. More to think about…

34. Extra PHP Interview Practice Questions
•What’s the difference between using mysql_ functions and PDO?
•Describe how inheritance works with PHP.
•Do you know what the PHP-FIG is? Describe it, describe the PSRs
you know.
•What classes would you create to build a basic Twitter-style
status system with OOP?
•What frameworks are you experienced in?
•What frameworks do you prefer? Why?
•Thoughts / experience with unit testing?

35. Exercise
•Build the Twitter style status system mentioned above
using PHP (it doesn’t have to run or be error-free). This
should be MVP and take less than 30 minutes.

36. What Else to Brush Up On
Our PHP interview questions here aren’t all-encompassing.
Here are some additional concepts that our mentors think
may be helpful for you brush up:
• Using htmlspecialchars namespaces and short hand array
styles []
• How to optimize code & how to pass user supplied data to
SQL to avoid injection.

37. Good Luck to Your Interview!!
For answers and more tutorials: https://www.codementor.io/php/tutorial/php-interview-
questions-sample-answers