Top 10 PHP interview questions 2024

In the dynamic world of web development, Hypertext Preprocessor (PHP) stands out as a powerful server-side scripting language. It is renowned for its efficiency in building dynamic websites and mobile APIs. With its extensive database support — including MySQL, Oracle, and PostgreSQL — PHP seamlessly integrates into HTML. This enables developers to manage dynamic content, session tracking, and even construct comprehensive e-commerce sites.

PHP is cost-effective and offers widespread server support, so it has become a pivotal skill in the industry. Because tech companies globally seek proficient PHP developers, understanding the core of PHP is crucial. This article discusses the top 10 PHP interview questions, offering insights to freshers and experienced professionals.

Basic PHP interview questions

1. What is PHP used for?

PHP is a versatile scripting language for developing dynamic and interactive websites. It's popular for its ability to embed directly into HTML. This streamlines the process of enhancing web pages with additional functionalities without relying on external files.

Here's a quick overview of what PHP is commonly used for:

• Access control to make sure only authorized users can view sensitive information

• Cookie management to easily access, set, and manage cookies, which are crucial for tracking user sessions and preferences

• Database operations become smoother with PHP interfaces

• Form and file handling to handle various tasks, from data submission and retrieval to file uploads and downloads

• Email integration into websites, enabling the automated sending and receiving of emails through your web applications

• PHP offers a range of system-level functions, such as opening, reading, and writing files, which are essential for robust web application development

2. What is the difference between 'print' and 'echo' in PHP?

Echo can show several strings simultaneously, separated by commas, while print is limited to one string per command. Echo works faster and more efficiently than print, which is relatively slower.

Syntax for 'echo':void echo ( string $arg1 [, string $... ] )For example:

echo "1st”, "2nd”, "3rd”, "Argument”, "Multiple Arguments";

Syntax for 'print':int print ( string $arg)For example:

print "Single Argument";

3. What are the types of variables in PHP? Explain with examples.

  In PHP, you can work with the following types of variables:  

• String

• Integer

• Float (also known as Double)

• Booleans

• NULL

• Array

• Resources

• Object

4. Explain the different types of errors in PHP.

In PHP, errors are categorized into notices, warnings, and fatal errors. Notices are minor, non-critical errors that aren't shown to users. Warnings, more significant yet not script-ending, are typically displayed to the user by default. Fatal errors are the most severe, often leading to the immediate cessation of the script.

5. Is PHP case-sensitive?

PHP shows partial case sensitivity. While constructs, function names, and class names in PHP are not case-sensitive, variable names are case-sensitive.For instance, in PHP, you can define user-defined functions in uppercase and then reference them in lowercase without any issues; they will still work correctly.

6. What is PEAR in PHP? What does it stand for?

PEAR stands for "PHP Extension and Application Repository." It serves as a framework and distribution system for reusable PHP components. It enhances PHP, offering advanced programming capabilities to web developers. PEAR has three classes: PEAR Core Components, PEAR Packages, and PECL Packages. It offers a wide range of PHP code snippets and libraries, along with a command-line interface for a smooth package installation.

7. What is $this in PHP?

In PHP, '$this' is a reserved keyword referencing the object that invokes a method. Mostly, it points to the object owning the method, but it can also refer to a different object if the method is called statically from another object's context. The '$this' keyword is exclusively relevant to methods within a class.

Advanced PHP interview questions

8. How do sessions work in PHP?

A PHP session enables the webserver to track information such as when you began using a website, your activities on the site, and when you exited the site. This tracking is necessary because, unlike personal computers or mobile devices, the web server does not have inherent user knowledge.

9. What are traits in PHP?

Traits in PHP serve as a tool for reusing code in languages with single inheritance. They help overcome some restrictions of single inheritance, so that you can apply the same methods across various independent classes within different class hierarchies.

10. Mention the different types of arrays in PHP.

PHP works with three types of arrays:

• Indexed Arrays: These are arrays with numerical indexes.

• Associative Arrays: Associative arrays, unlike traditional arrays that store elements in a strict linear index order, use named keys to store element values, allowing for more flexible data organization.

• Multidimensional Arrays: These consist of arrays that contain one or more other arrays.
  

Master PHP and excel at your next interview

To wrap it all up, we've journeyed through the essential aspects of PHP — its practical applications, distinguishing features, and advanced functionalities. This exploration offers a solid foundation for both newcomers and seasoned professionals gearing up for PHP interviews. We've highlighted the language's versatility and critical role in modern web development. Remember, mastering these key PHP concepts is not just about passing interviews — it's about excelling in a field that constantly evolves and innovates.

Step up your web development game with our ‘Web Development with PHP’ skill path. You'll understand everything from PHP basics to advanced concepts, and even learn how to integrate PHP with MySQL. It's a great chance to enhance your skills, build a solid PHP foundation, and stand out in your next web project or job interview.