Interview Questions to Hire a Skilled PHP Developer

77.5% of all the websites use PHP for their server-side programming, says the latest demographics received from W3Techs. These massive stats emphasize the considerable demand for PHP developers in the market.

Hypertext Pre-processor, commonly known as PHP, is an open-source language that is free to use, modify, and distribute. This language contributes to almost every stage of website development, from designing to testing to implementing the software.

Hence, PHP developers develop websites, software, and other programs using the PHP language. They are adept at creating and integrating plugins for frameworks, integrating front-end developers' work into back-end applications, and linking programs with external web services.

Let's explore more about PHP developers, such as the hiring of PHP developers, PHP developer interview questions, and so on.

Roles and Responsibilities of PHP Developer

• Develop user-facing elements with front-end developers.
• Create PHP modules that are effective, tested, and reusable
• Identify and resolve complex performance and architectural issues
• Data storage solution integration "may involve databases, key-value stores, blob stores, etc."
• Make specific parameters
• Maintained, tested, and troubleshoot databases and key product software to guarantee robust functionality and optimization.
• Participate throughout the entire development process.
• Observe best practices for your industry
• If necessary, create and implement additional features to make using associated procedures and tools easier

Skills and Qualification

• PHP software development background with a track record
• Knowledge of open-source initiatives such as Joomla, Drupal, Wikis, osCommerce, etc.
• An understanding of HTML, CSS, Javascript, and AJAX is required
• Enough familiarity with version control systems, relational databases, and web service development
• Knowledge of standard third-party APIs (Google, Facebook, eBay etc.)
• The ambition to create fresh, daring ideas, as well as a passion for the best design and coding methods
• A bachelor's or master's degree in engineering, computer science, or a related field
  

PHP Developer Interview Questions to Hire Skilled PHP Developers

1. What is PHP, and what are its advantages over other programming languages?  

Ans. PHP, also known as Hypertext Pre-processor, is a server-side (Backe-end) scripting language used as an open source during website, software, and other program development.

Advantages:

• It's easy to use
• It has a large active community and support
• It has versatility and flexibility in usage
• It's a fast and efficient scripting language
• It's a free-to-use, open-source language

2. Explain the difference between include and require statements in PHP.

There is no significant difference between the Include and require statements, except that need will produce a fatal error (E_COMPILE_ERROR) if it fails. While include will only result in an error (E_WARNING), after which the script will run normally.

3. How do you connect to a MySQL database in PHP?  

The mysqli extension for PHP offers a set of functions for working with MySQL databases and can be used to connect to a MySQL database.

4. What is object-oriented programming in PHP and what are its benefits?

In OOP, Object-Oriented Programming, objects and classes are used to organize and structure the code.

Benefits:

• Enables code reusability
• Offers code modularity
• Polymorphism

 5. Explain the use of sessions in PHP.

A session is a mechanism to save data (in variables) for usage on several pages at once. With sessions, the data is not saved on the user's machine, unlike cookies.

6. What are some security concerns in PHP, and how can they be mitigated?

Here are some security concerns with this open-source scripting language PHP:

• SQL Injection
• Cross-site scripting (XSS)
• Session Hijacking

To mitigate such concerns, the developer can

• Use prepared statements or parametric queries to avoid SQL injection
• Use secure session management strategies like cookie encryption and session timeouts for cross-site scripting (XSS)
• Use safe web server configuration and updated PHP version (as per 2023, Version 7) to avoid session hijacking

7. What are some standard functions in PHP for working with arrays?

Commonly found functions in PHP for working with arrays

• array_push(): adds one or more elements to the end of an array
• array_pop(): removes and returns the last element of an array
• array_shift(): removes and returns the first element of an array
• array_unshift(): adds one or more elements to the beginning of an array
• array_slice(): returns a portion of an array
• array_merge(): combines two or more arrays into a single array

 8. Explain the difference between GET and POST methods in PHP.

In the HTTP protocol, the GET and POST methods are both used to transfer data from the client to the server. However, the main distinction between the two is that the POST method is more secure because it carries the request parameter in the message body rather than the GET method's request parameter appended to the URL string.

9. What is a PHP framework, and what are some popular PHP frameworks?

A PHP framework serves as a building block for PHP web applications. By offering code libraries for frequently used functions, PHP frameworks help you write original code in lesser time.

Some popular PHP frameworks are Laravel, CodeIgniter, Yii, Laminas, FuelPHP, Symfony, Phalcon, PHPixie, and CakePHP.

10. Can you give an example of how you would use PHP to send an email from a web page?

Here's an example of sending email via PHP:

$to = 'recipient@example.com';

$subject = 'Test email';

$message = 'This is a test email sent from PHP';

$headers = 'From: sender@example.com';

11. Differentiate between static and dynamic websites.

A static website has constant content, ensuring every visitor sees the same thing on every page. The material of a dynamic website, on the other hand, is pulled instantly, allowing it to alter as the user does.

12. What is the primary use of PHP?

PHP is a server-side scripting language done from back-end. The primary use of PHP is to develop web pages, applications and software. It can be embedded into HTML to generate more dynamic content and interact with other databases.

13. What does PEAR in PHP stand for?

PEAR in PHP stands for PHP Extension and Application Repository.

14. In what manner a PHP script is run?

The preferred way of running a PHP script can be from your browser using a web server like Apache, Nginx, or IIS.

15. What kinds of variables are there in PHP?

• Integer: whole numbers (positive, negative, or zero)
• Float/Double: decimal numbers
• String: sequence of characters
• Array: an ordered collection of values
• Object: instances of classes
• Resource: a reference to an external resource (such as a database connection or file handle)
• Null: a variable with no value assigned to it
• Boolean: true or false values

16. What guidelines should you adhere to while naming variables in PHP?

• The dollar sign ($) and the variable's name come first in a variable.
• The underscore character or a letter must come first in a variable name.
• No number may begin a variable name.
• Only underscores (A-z, 0-9, and _) and alphanumeric characters are permitted in variable names.
• The capitalization of variable names ($age and $AGE are two distinct variables)

17. What is the most popular technique in PHP for hashing passwords?

The bcrypt hashing algorithm is currently the most popular. Several cryptographic methods, including md5, crypt, sha1, and bcrypt, are also frequently utilised in PHP.

18. What in PHP is NULL?

PHP NULL is a variable with no assigned value. Commonly it indicated the absence of a value or the failure of an operation.

19. In PHP, how are constants defined?

A constant is a term or identification for a simple value. The value cannot be altered while the script is running. A valid constant name begins with a letter or an underscore; the constant name does not have a $ sign before it.

20. What purpose does PHP's constant () function serve?

The purpose of PHP's constant () function is to retrieve the value of a constant.

Interview questions for experienced PHP Developer

21. How can PHP interact with HTML?

HTML can transmit data to PHP, and PHP can generate HTML. It's crucial that you learn how to retrieve variables from external sources before reading these faqs.

22. How does PHP interact with JavaScript?

As PHP is a server-side language and Javascript is a client-side language, they cannot interact directly. Consequently, since PHP can produce Javascript code that the browser can execute and since it is possible to send particular variables back to PHP via the URL, we can exchange variables.

23. What is the use of callback in PHP?

A function that receives an argument from another function.

24. What is the use of the function' imagetypes()'?

The imagetypes() function is an inbuilt PHP function which is used to give the image types supported by the current version of PHP inbuilt installed library.

25. What is needed to be able to use the image function?

To use the image function, GD (DIF Draw) library extension is required.

26. What is the main difference between require () and require_once()?

The require once () statement is the same as require () with the exception that PHP will determine whether the file has already been included and will not include (require) it again if it has.

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

There is only one distinction between the two (). If we use include once, code from a file that has already been included won't be included again (). signifies that include once() only opens the file once

28. How do you display text with a PHP script?

Using following format, you can display text with a PHP script:

• Echo command
• Print command

29. How do we use PHP to display information of a variable that's readable by a human?

Using print r(), humans can read the information about a variable that is displayed.

30. Explain the PHP error 'Parse error in PHP - unexpected T_variable at line x'.

This syntax error in PHP means that the parser came across a variable that wasn't expected.

31. How to export data into an Excel file?

• Click Excel under the Export group on the External Data tab.
• Check the suggested file name for the Excel workbook in the Export - Excel
• Spreadsheet dialogue box (Access uses the name of the source object).
• Choose the desired file format from the list in the File Format box.

32. How to execute a PHP script from the command line?

• Open your terminal
• Go to the directory that has the PHP script.
• Execute the PHP code
• See the result

33. What is the main difference between asp net and PHP?

Microsoft's ASP.NET platform is used to build both web and desktop applications. At the same time, PHP is an open-source platform that may be used for web development on various platforms.

34. What is overloading and overriding in PHP?

In overloading, many functions may share the same method signature but differ in the number of arguments. However, if overriding is used, several functions will have the same method signature and number of arguments.

35. What is the main difference between PHP 4 and PHP 5?

PHP5 is an object-oriented language, whereas PHP4 is more of a process language.

36. Is multiple inheritances supported in PHP?

Yes, multiple inheritances are supported in PHP.

37. How can we define a variable available in PHP script functions?

The global keyword allows one to use this feature.

38. What does the unset() function mean?

The unset() function eliminates the specified variables.

39. How do I escape data before storing it in the database?

With prepared statements and parameterized queries, a feature offered by most PHP database extensions, including MySQLi and PDO, we can escape data before storing it in a database.

40. How can we automatically escape incoming data?

We can automatically escape incoming data by using PHP's filter input() function with the FILTER SANITIZE STRING filter.

Additional Technical PHP Developer Interview Questions

1. What operation is needed when passing values through a form or an URL?

When passing values through a form or URL, the "HTTP GET" or "HTTP POST" type of operation is required.

2. Which function gives us the number of affected entries by a query?

Function' mysqli_affected_rows()' for My SQLi extension or 'mysql_affected_rows()' for MySQL extension gives us the number of affected entries by a query.

3. How can we check the value of a given variable is a number?

The is_numeric() function determines whether a variable is a numeric string or a number. If the variable is a number or a string of numbers, this function returns true (1); if not, it returns false/nothing.

4. How do I check if a given variable is empty?

The empty() function determines whether or not a variable is empty. Without an empty variable, this function returns false; otherwise, it returns true. The following values add up to nothing: 0. 42. What does the unlink() function mean?

5. How do you handle failures in execution with include () and require () functions?

To handle failures in execution with include () and require () functions, use the following techniques;

• Use 'if' statements
• Use 'try...catch' blocks
• Try the 'require_once ()' function

Use iMocha to hire the best PHP Developers

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Online PHP Technical test- High level

PHP Coding Test (Basic)

PHP Coding Test (Medium)

PHP Web Developer Test

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FAQs

1. How to interview a PHP developer?

To interview a PHP Developer, recruiters can use top recruitment tools available in the market, such as iMocha, and automate the entire hiring cycle. In addition, recruiters can also ask open-end PHP developer interview questions such as PHP frameworks, databases, front-end technologies, and more.

2. What are some good logical programming questions for a PHP interview?

• Write a PHP function to check whether a given string is a palindrome or not.
• Write a PHP program to find the largest and smallest numbers in an array of integers.
• Create a PHP application to calculate the sum of a given number's digits.
• Create a PHP application that counts the number of times a specific character appears in a string.

  3. What skills do PHP developers need?

• Understanding of the PHP programming language.
• Knowledge of PHP frameworks like Yii, CodeIgniter, and Laravel.
• Working knowledge of front-end technologies like HTML, CSS, and JavaScript.
• SQL expertise and working knowledge of databases like MySQL and PostgreSQL.
• Knowledge of version control programs like Git.
• Code writing skills that are clear, effective, and well-documented.
• Experience with problem-solving and debugging.
• Having effective communication abilities and the capacity for teamwork.