Top Laravel & PHP Interview Questions Every Developer Should Master

Recently a community post attracted many programmers, sharing Laravel and PHP interview questions; the author compiled concise answers for developers preparing for interviews.

PHP Module

What are the differences between PHP7 and PHP5? New features include roughly double performance, the combined comparison operator (<=>), scalar type declarations, return type declarations, try...catch for multi‑condition error handling, and anonymous classes instantiated via new class .

Why is PHP7 faster than PHP5? Variable storage size is reduced, array structures are improved with combined hash tables, and the function call mechanism is optimized, all boosting execution speed.

Laravel Module

What is a service provider? It is the central bootstrap for all Laravel applications, registering service container bindings, event listeners, middleware, routes, and other core services.

What is the IoC container? Inversion of Control (IoC), also known as Dependency Injection, dynamically injects required dependencies into objects at runtime.

What are Facades? A design pattern offering a static‑like interface to classes registered in the IoC container, simplifying usage and testing.

What are Contracts? Interfaces that define core framework services, promoting low coupling and simplicity.

What is the principle of dependency injection? It decouples objects by injecting required dependencies rather than having objects create them directly.

What is Composer and how does it work? Composer is PHP's dependency manager; it downloads packages from packagist.org, resolves version constraints, and installs them into the project.

Cache

Difference between Redis and Memcached: Redis supports richer data types (String, Hash, List, Set, Sorted Set), offers persistence and transactions, and runs on a single core; Memcached provides simple key‑value storage with higher memory efficiency and multi‑core usage.

How does Redis achieve persistence? Through RDB snapshots that save the in‑memory state to disk and AOF (Append‑Only File) that logs every write operation.

Database

What is an index and its purpose? An index is a special file containing pointers to table rows, accelerating data retrieval. Common types include primary key, unique, composite, and full‑text indexes.

Principles for creating indexes: follow the left‑most prefix rule, choose columns with high selectivity, and avoid creating redundant indexes.

How to handle high concurrency? Use caching, optimize database queries, and employ load balancing.

Additional common interview topics include sharding design, MySQL deadlock handling, understanding closures, PHP memory reclamation, solving memory overflow, database optimization methods, Laravel runtime and routing principles, cookie vs session handling, server clustering, load balancing, reverse proxy, and common server commands.

Note: Interviewers also evaluate motivation, thinking ability, communication skills, and sometimes personal aspects.

Answers are available on GitHub: https://github.com/todayqq/caseInterviewQuestions