Ultimate Guide to PHP Interview Questions and Answers in 2024

What is PHP Programming Language

PHP is one of the world’s most renowned scripting languages which is used for web development. PHP development is one of the most coveted jobs in the world of web development as well and this creates a lot of competition when it comes to applying for jobs. With that in mind, these PHP interview questions are carefully curated with the questions that have the highest probability of occurrence in interviews to help you ace it and land the job.

Why is PHP Programming Language

PHP finds itself among the top languages because of its ability to have a large impact on the outcome with very little code. This amount of efficiency has been the main requirement for the past couple of years in the industry. Now, seeing this, companies across the globe are investing a good amount of money in hiring proficient PHP developers to fit these shoes and work effectively. These heavily asked top core PHP interview questions will give you the edge that is required to approach the questions effectively and answer them in a concise manner.

Hiring Jobs For PHP Programming Language

Actually, the hiring process can be different for different companies, It depends on the company size. If you are going for an interview in a big company then most of the time, you will face theoretical questions, all related to PHP and Mysql. For example:

Q1: Differentiate between static and dynamic websites.

A: Static websites contain fixed, unchanging content and offer limited interactivity. Dynamic websites, on the other hand, generate content on-the-fly, often from a database or user input. They adapt to user interactions and changing data, providing a more interactive and personalized user experience.

Q2: What is PHP most used for?

A: PHP is primarily used for web development. It excels in creating dynamic web applications and websites, offering flexibility, compatibility with various databases, and efficient server-side scripting.

Q3: Is PHP a case-sensitive scripting language?

A: Yes, PHP is case-sensitive. It distinguishes between uppercase and lowercase letters in variable names and function calls, so "myVar" and "myvar" are considered different in PHP.

Q4: What is the meaning of PEAR in PHP?

A: PEAR stands for "PHP Extension and Application Repository." It's a framework and distribution system for reusable PHP components, providing a vast library of packages to simplify PHP application development.

Q5: How is a PHP script executed?

A: When a user requests a PHP page, the web server processes the PHP code using a PHP interpreter, which reads and interprets the code line by line. The server then sends the output to the user's browser.

Q6: What are the types of variables present in PHP?

A: PHP supports various variable types, including integers, floats, strings, and arrays, among others. Each type serves a specific purpose in storing and manipulating data.

Q7: What are the variable-naming rules to follow in PHP?

A: Variable names in PHP are case-sensitive and must start with a dollar sign ($). They can contain letters, numbers, and underscores, but they cannot start with a number.

Q8: What are the main characteristics of a PHP variable?

A: PHP variables hold data values that can change during the script execution. They are loosely typed, meaning you don't need to declare the data type when defining a variable. PHP variables are also case-sensitive.

Q9: What is NULL in PHP?

A: In PHP, NULL represents the absence of a value or an uninitialized variable. It's used to indicate that a variable has not been assigned any value.

Q10: How are constants defined in PHP?

A: Constants in PHP are defined using the define() function. They differ from variables in that their values remain constant throughout the script's execution and are typically written in uppercase.

Q11: What are some of the popular frameworks in PHP?

A: Popular PHP frameworks include Laravel, Symfony, and CodeIgniter. These frameworks provide a structured foundation for building web applications and come with pre-built modules and tools to streamline development.

Q12: What are the types of arrays supported by PHP?

A: PHP supports various types of arrays, including indexed arrays, associative arrays, multidimensional arrays, and more. Each type serves specific data organization needs.

Q13: How does the 'foreach' loop work in PHP?

A: The 'foreach' loop is used to iterate over arrays or other iterable objects. It iterates through each element of the array, executing a specified block of code for each element.

Q14: What are the data types present in PHP?

A: PHP supports data types such as integers, floats (floating-point numbers), strings, booleans, arrays, objects, resources, NULL, and more. Each data type is used for specific data handling purposes.

Q15: What is the use of constructors and destructors in PHP?

A: Constructors are special methods in PHP classes used to initialize objects when they are created. Destructors, on the other hand, are used to perform cleanup operations before an object is destroyed.

Q16: Is it possible to set infinite execution time in PHP?

A: While it's not recommended for security reasons, you can increase the maximum execution time for a PHP script using the set_time_limit() function. Setting it to zero effectively allows infinite execution.

Q17: What are some of the top Content Management Systems (CMS) made using PHP?

A: Popular PHP-based CMSs include WordPress, Drupal, Joomla, and Magento. These platforms empower users to create and manage websites with ease.

Q18: What is the most used method for hashing passwords in PHP?

A: PHP developers commonly use the password_hash() and password_verify() functions for secure password hashing and verification, following best practices for password security.

Q19: What is the difference between ASP.NET and PHP?

A: ASP.NET is a Microsoft framework, while PHP is a server-side scripting language. ASP.NET primarily runs on Windows servers, while PHP is platform-independent. The choice between them often depends on project requirements and hosting environments.

Q20: What are sessions and cookies in PHP?

A: Sessions and cookies are mechanisms for maintaining user state in PHP. Sessions store user data on the server, while cookies store data on the user's browser. They are commonly used for user authentication and personalization.

Q21: Does PHP support variable length argument functions?

A: Yes, PHP supports variable-length argument functions through the use of func_get_args() and func_get_arg() functions, allowing you to create flexible functions that accept a variable number of arguments.

Q22: What is the use of session_start() and session_destroy() functions?

A: session_start() initiates a session, allowing you to store and retrieve user-specific data across multiple pages. session_destroy() ends the session, clearing all session data.

Q23: What are the different types of PHP errors?

A: PHP errors include syntax errors, fatal errors, warnings, notices, and more. Proper error handling is essential for debugging and maintaining code quality.

Q24: What is the use of $message and $$message in PHP?

A: $message represents a variable, while $$message represents a variable variable. The latter allows you to create variable names dynamically.

Q25: Differentiate between GET and POST methods in PHP.

A: GET and POST are HTTP request methods. GET appends data to the URL, making it visible in the address bar. POST sends data in the request body, keeping it hidden. POST is typically used for sensitive data, while GET is suitable for non-sensitive data retrieval.

Q26: What is the use of lambda functions in PHP?

A: Lambda functions, also known as anonymous functions, are small, unnamed functions that can be used as arguments to other functions or assigned to variables. They are particularly useful for callbacks and one-off operations.

Q27: Differentiate between compile-time exception and runtime exception in PHP.

A: Compile-time exceptions, also known as syntax errors, are detected during script compilation. Runtime exceptions occur during script execution and are often caused by issues like division by zero or accessing undefined variables.

Q28: What is the meaning of type hinting in PHP?

A: Type hinting allows you to specify the data type of a function's parameters, ensuring that only values of the specified type are accepted as arguments. This enhances code reliability and readability.

Q29: What are the steps to create a new database using MySQL and PHP?

A: To create a new database using MySQL and PHP, you need to connect to MySQL, send SQL commands to create the database, and handle any errors that may occur during the process. Once created, you can interact with the database using PHP.

Q30: What rules are there for determining the "truth" of any value that isn't already a Boolean value?

A: In PHP, values that evaluate to true include non-empty strings, non-zero numbers, arrays with elements, objects, and more. Values that evaluate to false include empty strings, zero, NULL, empty arrays, and false.

Q31: How can we encrypt a password using PHP?

A: You can encrypt passwords using password hashing functions like password_hash(). This method securely hashes passwords with a salt, providing enhanced security against attacks.

Q32: Explain how to submit a form without a submit button.

A: You can submit a form without a visible submit button using JavaScript. You trigger form submission programmatically by calling the submit() method on the form element.

Q33: How can we increase the execution time of a PHP script?

A: To increase the maximum execution time of a PHP script, you can use the set_time_limit() function, setting it to a higher value. Be cautious when doing this to avoid security and performance issues.

Q34: What is Zend Engine?

A: The Zend Engine is the scripting engine that powers PHP. It is responsible for parsing, compiling, and executing PHP code. It also provides memory management and other core functionalities.

Q35: How can we execute a PHP script using a command line?

A: To execute a PHP script from the command line, you can use the php command followed by the script's filename. This method is useful for running PHP scripts independently of a web server.

Q36: What is Memcache?

A: Memcache is an in-memory caching system used to speed up database-driven websites by caching data in RAM. It reduces the need to fetch data from the database, improving site performance.

Q37: What is meant by PEAR in PHP?

A: PEAR, or "PHP Extension and Application Repository," is a framework and distribution system for reusable PHP components. It offers a vast collection of libraries and packages to streamline PHP application development.

Q38: Explain soundex() and metaphone()

A: soundex() and metaphone() are phonetic algorithms used to index words by their pronunciation. They are often used in spelling correction and search applications to find words that sound similar to a given input.

Q39: What is Smarty in PHP?

A: Smarty is a popular PHP template engine used for separating application logic from presentation. It simplifies the creation of dynamic web pages, making them more maintainable and organized.

Q40: What library is used for PDF in PHP?

A: For working with PDFs in PHP, the TCPDF and FPDF libraries are commonly used. These libraries provide functions for creating and manipulating PDF documents.

Q41: What is .htaccess, and why do we use it?

A: .htaccess is a configuration file used on Apache web servers to customize server settings for a directory or its subdirectories. It allows you to control URL rewriting, access control, and other server configurations without modifying the main server configuration file.

Q42: What are magic methods in PHP?

A: Magic methods are special methods in PHP classes with double underscores (e.g., __construct and __toString). They provide predefined functionality, such as constructor and toString, and are automatically called in certain situations, enhancing the flexibility of PHP classes.

Q43: What are the popular Content Management Systems (CMS) in PHP?

• WordPress: WordPress is a free and open-source content management system (CMS) based on PHP & MySQL. It includes a plug-in architecture and template system. It is mostly connected with blogging but supports another kind of web content, containing more traditional mailing lists and forums, media displays, and online stores.
• Magento: Magento is an open source E-trade programming, made by Varien Inc., which is valuable for online business. It has a flexible measured design and is versatile with many control alternatives that are useful for clients. Magento utilizes E-trade stage which offers organization extreme E-business arrangements and extensive support network.
• Drupal: Drupal is a CMS platform developed in PHP and distributed under the GNU (General Public License).
• Joomla: Joomla is a free and open-source content management system (CMS) for distributing web content, created by Open Source Matters, Inc. It is based on a model-view-controller web application framework that can be used independently of the CMS.

Q44. How would you sort an array of strings to their natural case-insensitive order, while maintaing their original index association?

For example, the following array:

array(
 '0' => 'z1',
 '1' => 'Z10',
 '2' => 'z12',
 '3' => 'Z2',
 '4' => 'z3',
)

With these answers to the top PHP interview questions, you're well-equipped to excel in your PHP interview in 2024. Mastering these concepts and demonstrating your knowledge and skills will set you on the path to a successful PHP development career.