12 Top PHP Interview Questions and Answers (2023)
Want to interview PHP developers? Here are the best PHP interview questions. Use them to interview your candidates and identify top performers at your next interview. Read on!
PHP interviews
PHP (Hypertext Preprocessor) is an open-source general-purpose scripting language that works well for web development and can be embedded into HTML.
To hire PHP developers, you need the right PHP interview questions. We’ve compiled our favorites to help you find the best match for your job.
Remember that PHP interviews are just one part of the recruitment process. You also need to assess your candidates’ technical skills. You can read more about our coding challenges here.
Read on for our favorite questions!
Beginner PHP interview questions
What should you ask junior PHP developers? Here are our favorite beginner-friendly alternatives. These questions are all about helping you understand how well your candidates can explain what PHP is and when it’s used. They aren’t word-for-word answers, but rather an indicator of what candidates can include in their answers.
1. What is PHP?
Answer:
PHP, which stands for Hypertext Preprocessor, is an open-source, server-side scripting language that works well for creating dynamic websites and mobile APIs.
It supports databases such as MySQL, PostgreSQL, Solid, Oracle, and Sbase.
The code is embedded in HTML. PHP is used for session tracking, in databases, managing dynamic content, and building websites. Most web hosting servers support PHP.
2. What are the pros of PHP?
Answer:
The pros of PHP are:
- It has a large base of references and educational materials
- The websites load better
- Database connectivity works well
- There is a big community of specialists
- Many open-source addons
- Inexpensive website hosting
- Flexibility
- Works well with HTML
3. And the cons?
Answer:
The cons of PHP are:
- It doesn’t work great with big, content-based web applications
- It’s open-source, so it’s not very secure
- Change or modification in the core behavior of online applications isn’t possible
- If more features are used, online applications don’t work as well
- PHP doesn’t include debugging tools and so it doesn’t work great in case of errors (there are only a few debugging tools)
4. What are the popular frameworks in PHP?
Answer:
They are, among others:
- CodeIgniter
- Yii 2
- Symfony
- CakePHP
Advanced PHP interview questions
Answer:
What should you ask more senior PHP developers? Here below are some of our favorite questions. They focus more on the technical understanding of PHP and go deeper into the details.
5. How do echo and print differ from each other in PHP?
Answer:
They are pretty much the same in PHP and they’re both used to output data to the screen. The only differences are that echo doesn’t return a value, but print does (of 1, which is why print can be used in expressions).
Print can only take a single argument, while echo accepts multiple parameters.
6. What are the main errors in PHP?
Answer:
There are three main errors in PHP. These are:
Notices: Non-critical errors that happen during the script execution. For example, accessing an undefined variable.
Warnings: More important errors, but scripts continue the execution.
Fatal: This error causes a termination of the script execution. For example, this can happen if someone accesses a property of a non-existent object or require() a non-existent file.
7. What is a session?
Answer:
A session is a logical object created by the PHP engine that preserves data across subsequent HTTP requests. They typically store temporary data so that they allow PHP pages to offer a complete functional transaction for the same user. In other words, they maintain a user’s/browser’s data.
8. What are the characteristics of PHP variables?
Answer:
PHP variables have some important characteristics, including:
- They are denoted with a leading dollars ign ($)
- Variables are assigned with the = operator so that variables are evaluated on the left side and expressions on the right
- The value of a variable is the value of the most recent assignment
- Variables that are used before they are assigned have default values
- PHP variables don’t have intrinsic types, but they can be used to store a number of a string of characters
9. Can PHP and JavaScript interact?
Answer:
No, they can’t interact directly. PHP is a server-side language, whereas JavaScript is a client-side language. That said, they can exchange variables because PHP can generate JavaScript code through a browser and specific code can be passed back to PHP via the URL.
10. What is a Parser in PHP?
Answer:
A PHP parser is software that converts source code that the computer can understand. The parser converts a set of instructions given in the form of PHP code into a machine-readable format. Use the token_get_all() function to parse PHP code.
11. What are the three scope levels available in PHP?
Answer:
This question highlights your candidate’s understanding of the accessibility of code. The three scope levels are:
- Private: This level is visible only in its own class.
- Public: This level is visible to any other code accessing the class.
- Protected: This level is visible only to classes parent(s) and classes that extend the class.
12. Can you set an infinite execution time for a PHP script?
Yes, if you add the set_time_limit(0) at the beginning of a script, the time of execution is set to infinite so that the PHP error ‘maximum execution time exceeded’ doesn’t show. You can also specify this in the php.ini file.
Over to you!
That’s it! Those are the most important PHP interview questions.
That said, your interview is only Step 1. Step 2 is to assess your candidates. At CodeSubmit, we offer industry-leading coding challenges to help you do so.
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