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PHP

100 PHP interview questions

Only coding challenges
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PHP Fundamentals


  • 1.

    What does PHP stand for and what is its main purpose?

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  • 2.

    How do you execute a PHP script from the command line?

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  • 3.

    Can you describe the differences between PHP 5 and PHP 7/8?

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  • 4.

    What are the common ways to embed PHP into HTML?

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  • 5.

    How would you create a PHP variable and how are they scoped (global, local, static)?

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  • 6.

    Explain the data types that are supported in PHP.

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  • 7.

    How does PHP handle error reporting?

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  • 8.

    What is the purpose of php.ini file?

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  • 9.

    How do you define a constant in PHP?

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  • 10.

    Can you describe the lifecycle of a PHP request?

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  • 11.

    Explain the use of sessions in PHP.

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  • 12.

    How does PHP support cookies?

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  • 13.

    Describe the _$_GET, _$POST, and _$REQUEST superglobal arrays.

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  • 14.

    How can you prevent form submission data from being injected with malicious code?

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  • 15.

    What is the significance of “htmlspecialchars” and “strip_tags” in PHP?

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PHP Advanced Features


  • 16.

    Explain late static binding in PHP.

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  • 17.

    What is a namespace in PHP and why are they used?

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  • 18.

    Can you describe what a closure is in PHP and provide an example?

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  • 19.

    Explain the concept of traits in PHP and how they’re used.

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  • 20.

    How does PHP handle exceptions and error handling?

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  • 21.

    Discuss type declarations and return type in PHP 7/8.

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  • 22.

    What is a generator in PHP and when would you use one?

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  • 23.

    What are anonymous classes and how do you use them in PHP 7/8?

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  • 24.

    Explain how to use the “yield” keyword in PHP.

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  • 25.

    Describe the difference between “include”, “include_once”, “require”, and “require_once”.

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PHP Functions and Classes


  • 26.

    How do you declare a function in PHP?

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  • 27.

    What are magic methods in PHP?

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  • 28.

    How are objects passed in PHP - by value or by reference?

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  • 29.

    What are interfaces and how are they different from abstract classes in PHP?

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  • 30.

    Explain how you can prevent the class from being inherited.

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  • 31.

    What are getters and setters, and why would you use them?

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  • 32.

    Describe method overloading in PHP.

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  • 33.

    How would you use a static method or property in a class?

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  • 34.

    What is the purpose of the “final” keyword in PHP?

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  • 35.

    Discuss dependency injection in PHP.

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PHP Database Interaction


  • 36.

    How does PHP interact with databases?

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  • 37.

    What is PDO (PHP Data Objects) and how it is different from MySQLi?

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  • 38.

    Explain a prepared statement and why it’s used in PHP.

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  • 39.

    How can you perform a transaction with PDO?

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  • 40.

    Describe the process of connecting to a MySQL database using PDO.

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  • 41.

    What mechanisms does PHP provide for accessing NoSQL databases?

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  • 42.

    How would you handle database errors in PHP?

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  • 43.

    Can you explain how ORM tools like Laravel’s Eloquent or Doctrine work in PHP?

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  • 44.

    How does PHP handle database connection persistence?

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  • 45.

    Explain how you would use PHP to handle multiple database connections.

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PHP Security Practices


  • 46.

    What is SQL Injection and how can it be prevented in PHP?

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  • 47.

    How does PHP handle password hashing?

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  • 48.

    Explain Cross-Site Scripting (XSS) and how to prevent it with PHP.

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  • 49.

    Discuss prevention of CSRF (Cross-Site Request Forgery) in PHP.

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  • 50.

    Describe the concept of session hijacking and how PHP can safeguard against it.

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  • 51.

    How would you secure file uploads in PHP?

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  • 52.

    What are the best practices for securing PHP applications on shared hosts?

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  • 53.

    Explain how to securely store sensitive data, such as API keys, in PHP applications.

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  • 54.

    Discuss the use of HTTPS and how PHP can enforce secure connections.

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  • 55.

    What are PHP filters and how can they be used to validate and sanitize data?

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PHP Performance Optimization


  • 56.

    How can you improve the performance of a PHP application?

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  • 57.

    What is opcode caching and how can it be used in PHP?

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  • 58.

    Discuss the use of content delivery networks (CDNs) in relation to PHP applications.

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  • 59.

    How does session storage affect PHP performance and what alternatives exist?

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  • 60.

    Explain how to profile a PHP application for performance issues.

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  • 61.

    What is lazy loading and how can it be implemented in PHP?

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  • 62.

    Discuss the use of indexes in databases and how it relates to PHP performance.

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  • 63.

    How can PHP leverage browser caching?

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  • 64.

    What are some common PHP bottlenecks and how do you resolve them?

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  • 65.

    Describe the concept of connection pooling and its relevance to PHP applications.

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PHP Testing and Debugging


  • 66.

    What tools can you use for unit testing in PHP?

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  • 67.

    How do you debug PHP scripts?

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  • 68.

    What is the purpose of the Xdebug extension for PHP?

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  • 69.

    Discuss the benefits and methods of integration testing in PHP applications.

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  • 70.

    How would you set up a staging environment for testing PHP applications?

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  • 71.

    Describe how assertions can be used in PHP.

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  • 72.

    What is code coverage and how can it be measured in PHP?

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  • 73.

    Discuss the role of continuous integration in PHP development workflows.

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  • 74.

    Explain the “var_dump” and “print_r” methods used in debugging PHP code.

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  • 75.

    How can you track down and fix memory leaks in PHP?

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PHP Configuration and Deployment


  • 76.

    What is the typical workflow for deploying a PHP application?

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  • 77.

    How does PHP handle file uploads and server file management?

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  • 78.

    Discuss the various ways you can configure PHP logging.

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  • 79.

    What are environment variables in PHP and how can they be used?

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  • 80.

    How would you automate the deployment of a PHP application?

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  • 81.

    Explain the role of Composer in PHP development.

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  • 82.

    Describe a virtual host and how it is configured for PHP applications.

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  • 83.

    How can containerization be utilized in PHP application deployments?

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  • 84.

    Discuss .htaccess files and their importance in PHP configurations.

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  • 85.

    What measures do you take to ensure a smooth rollout of new PHP code in production environments?

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PHP Modern Development Practices


  • 86.

    How has PHP integrated with front-end JavaScript frameworks?

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  • 87.

    Discuss PHP’s support for HTTP/2.

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  • 88.

    Explain the use of WebSockets in PHP.

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  • 89.

    Describe the role of PHP in a microservices architecture.

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  • 90.

    How does PHP handle REST API development?

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  • 91.

    Discuss the use of GraphQL with PHP.

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  • 92.

    What is serverless architecture and can PHP be used in such an environment?

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  • 93.

    How do modern PHP frameworks handle route-based actions?

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  • 94.

    Explain how MVC architecture is implemented in PHP.

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  • 95.

    Describe how PHP can be used for command-line scripting.

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PHP Frameworks


  • 96.

    What are the benefits of using a PHP framework?

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  • 97.

    Can you compare Laravel and Symfony?

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  • 98.

    How would you choose between different PHP frameworks for a project?

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  • 99.

    Discuss the role of template engines in PHP frameworks.

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  • 100.

    Explain the event-driven architecture in PHP frameworks like Laravel.

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