43 PHP interview questions with answers

All PHP interview questions

• What is PHP and what does it stand for?

• What are PHP superglobals? Give examples.

• What's the difference between $_GET and $_POST?

• What are PHP data types and what are the main ones?

• What is the difference between == and === operators?

• How do you work with arrays in PHP? What are the main types?

• What are common string functions in PHP?

• What is the difference between include and require?

• How do you handle form data in PHP?

• What are PHP error types and how are they handled?

• How do you define and use constants in PHP?

• What are classes and objects in PHP? What's the difference?

• What is inheritance in PHP?

• Does PHP support multiple inheritance? How do you achieve similar functionality?

• What are interfaces and when should you use them?

• What are Traits in PHP and how do they solve problems?

• What are magic methods in PHP? Give examples.

• What is the difference between static and instance methods?

• What are access modifiers (public, private, protected)?

• What is PDO and how does it prevent SQL injection?

• How do PHP sessions work and what's the difference from cookies?

• What are namespaces and why should you use them?

• What is autoloading and how do you implement it?

• What are generators in PHP and when do you use them?

• What is the difference between unset() and unlink()?

• How do you prevent Cross-Site Scripting (XSS) attacks in PHP?

• How do you handle exceptions in PHP?

• What is type hinting and why is it important?

• What are abstract classes and when do you use them?

• What are typed class constants in PHP 8.3 and why are they useful?

• What are Fibers in PHP 8.1 and how are they different from threads?

• What are the constraints of readonly classes introduced in PHP 8.2?

• What are Enums in PHP 8.1 and when should you use them instead of constants?

• What are Value Objects in PHP and when should you use them instead of primitives?

• Why store passwords with `password_hash()` / `password_verify()` instead of `md5`/`sha1`?

• What is a nullable type (`?type`) in PHP?

• What are streams and stream wrappers in PHP?

• What is OPcache and how does it optimize PHP performance?

• What principles make up SOLID (applied in PHP)?

• What is Composer and how does Laravel use it?

• How does PHP 8's `match` differ from `switch`?

• What problems do PHP 8 named arguments and constructor property promotion solve?

• What are PHP 8 attributes? How do they differ from docblock annotations, and how do frameworks use them?