400 PHP Interview Questions with Answers 2026

The PHP Interview Practice Questions and Answers course is my personal mission to help you transition from "just knowing code" to demonstrating true engineering mastery in high-pressure technical interviews. I have meticulously crafted these practice exams to go far beyond simple syntax, challenging you to think critically about memory management, design patterns, and modern backend architecture. Whether you are navigating the nuances of type juggling, optimizing complex SQL queries within a Laravel environment, or securing a REST API against the latest OWASP threats, I provide the exact level of depth needed to impress senior-level hiring managers.

I don’t just give you the right answer; I break down the "why" behind every single line of code, ensuring you develop a mental model of PHP that stands up to the most rigorous questioning. By focusing on the intersection of theoretical computer science and practical, production-grade engineering, I’ve built a resource that bridges the gap between a hobbyist and a professional developer, giving you the confidence to lead architectural discussions and solve real-world performance bottlenecks. Exam Domains & Sample TopicsCore Fundamentals: Superglobals, closures, generators, and strict typing.

Object-Oriented Design: SOLID principles, PSR-4, and advanced design patterns. Web & API Ecosystem: JWT/OAuth, HTTP lifecycle, and Middleware. Data & Scaling: PDO, Redis caching, query optimization, and transactions.

Security & DevOps: XSS/CSRF prevention, PHPUnit, Docker, and CI/CD. Sample Practice QuestionsQuestion 1: Which of the following best describes the behavior of anonymous functions (closures) regarding variable scope in PHP? A) They automatically inherit all variables from the parent scope.

B) They use the global keyword to access parent variables. C) They require the use language construct to inherit variables from the parent scope by value (or reference). D) They cannot access any variables outside their own local scope.

E) They only have access to superglobals like $_SESSION and $_GET. F) They inherit variables from the parent scope only if the function is defined as static. Correct Answer: COverall Explanation: In PHP, closures do not automatically capture variables from the surrounding scope.

To utilize a variable from the parent scope inside the closure, you must explicitly pass it via the use clause. Option Explanations:A: Incorrect; PHP does not support automatic lexical scoping for closures like JavaScript. B: Incorrect; global pulls from the global script scope, not the immediate parent/function scope.

C: Correct; This is the standard syntax for lexical scoping in PHP. D: Incorrect; They can access external variables if explicitly imported. E: Incorrect; All functions have access to superglobals, but closures can access more via use.

F: Incorrect; static closures actually prevent the automatic binding of $this. Question 2: In the context of the SOLID principles, what is the primary goal of the "Interface Segregation Principle"? A) Classes should be open for extension but closed for modification.

B) A class should have only one reason to change. C) Objects of a superclass should be replaceable with objects of its subclasses. D) Depend upon abstractions, not concretions.

E) Clients should not be forced to depend upon interfaces that they do not use. F) Every interface must be implemented by at least two distinct classes. Correct Answer: EOverall Explanation: The Interface Segregation Principle (ISP) advocates for splitting large, "fat" interfaces into smaller, more specific ones so that implementing classes only need to concern themselves with methods that are relevant to them.

Option Explanations:A: Incorrect; This describes the Open/Closed Principle. B: Incorrect; This describes the Single Responsibility Principle. C: Incorrect; This describes the Liskov Substitution Principle.

D: Incorrect; This describes the Dependency Inversion Principle. E: Correct; This is the core definition of ISP. F: Incorrect; There is no numerical requirement for implementations in SOLID.

Question 3: How does the yield keyword function within a PHP Generator? A) It terminates the script execution and returns a status code. B) It pauses function execution and returns a value to the caller, resuming from that point when called again.

C) It sends an immediate header redirect to the browser. D) It is an alias for the return keyword in modern PHP versions. E) It forces the garbage collector to clear the current function's memory.

F) It allows a function to return multiple values simultaneously as a standard array. Correct Answer: BOverall Explanation: Generators provide an easy way to implement iterators without the overhead of implementing a class. The yield keyword provides the value to the loop and "freezes" the state of the function.

Option Explanations:A: Incorrect; exit or die handles termination. B: Correct; This state-saving behavior is what makes generators memory-efficient. C: Incorrect; header() handles redirects.

D: Incorrect; yield and return have very different behaviors in terms of state. E: Incorrect; yield actually helps memory but isn't a GC trigger. F: Incorrect; It returns a Generator object, not a standard array.

Welcome to the best practice exams to help you prepare for your PHP Interview Practice Questions and Answers. You can retake the exams as many times as you wantThis is a huge original question bankYou get support from instructors if you have questionsEach question has a detailed explanationMobile-compatible with the Udemy app30-day money-back guarantee if you're not satisfiedI hope that by now you're convinced! And there are a lot more questions inside the course.

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