Top questions with answers asked in MNC on Codeigniter

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CodeIgniter interview questions along with their answers:

  1. What is CodeIgniter, and what are its key features?
    • Answer: CodeIgniter is an open-source PHP framework for building dynamic web applications. It follows the MVC (Model-View-Controller) architectural pattern and provides a rich set of libraries and helpers to simplify the development process. Some key features of CodeIgniter include:
      • Lightweight and fast performance.
      • MVC architecture for better organization of code.
      • Powerful database abstraction with support for multiple platforms (MySQL, PostgreSQL, SQLite, etc.).
      • Form and data validation with built-in validation rules.
      • Security features such as XSS (Cross-Site Scripting) filtering, CSRF (Cross-Site Request Forgery) protection, and encryption.
      • Session management and caching mechanisms for improved performance.
      • Error logging and debugging tools for easy troubleshooting.
  2. Explain the difference between CodeIgniter 3 and CodeIgniter 4.
    • Answer:
      • CodeIgniter 3: CodeIgniter 3 is the older version of the framework, which follows the traditional PHP structure and uses PHP 5.x syntax. It relies on the Model-View-Controller (MVC) architecture and provides a set of libraries and helpers for common tasks such as database access, form validation, session management, etc.
      • CodeIgniter 4: CodeIgniter 4 is the latest version of the framework, which introduces several improvements and modernizations over CodeIgniter 3. It adopts PHP 7.x syntax and provides better support for namespaces, autoloading, and Composer integration. CodeIgniter 4 also introduces features such as enhanced routing, model support for namespaces, command-line tools, and improved security features.
  3. How does routing work in CodeIgniter?
    • Answer: Routing in CodeIgniter refers to the process of mapping URLs to specific controller methods. CodeIgniter uses a routing configuration file (app/Config/Routes.php) to define custom routes and specify the corresponding controller and method for handling each route. Routes can be defined using simple pattern matching or regular expressions. By default, CodeIgniter follows the convention of mapping URLs to controller classes/methods based on the URI segments. For example, the URL /controller/method/params will call the method() method of the Controller class with the specified parameters.
  4. What is a CodeIgniter controller, and how is it used?
    • Answer:
      • A CodeIgniter controller is a PHP class responsible for handling user requests and generating responses. Controllers contain methods (controller actions) that correspond to different actions or pages within the application. Each controller method is responsible for processing the request, loading necessary models or views, and returning the response to the client. Controllers typically extend the CodeIgniter\Controller base class and are stored in the app/Controllers directory. They can be accessed via URLs by specifying the controller name and method name in the URI.
  5. Explain the role of helpers in CodeIgniter.
    • Answer: Helpers in CodeIgniter are utility functions that provide common functionality and assist in performing tasks such as form handling, file operations, string manipulation, URL generation, etc. Helpers are typically standalone functions and are not associated with any specific class. They can be loaded dynamically within controllers, models, or views using the helper() function or autoloaded in the configuration. CodeIgniter provides a set of built-in helpers, such as URL helper, form helper, file helper, and session helper. Additionally, developers can create custom helpers to encapsulate reusable code and extend the framework’s functionality.