CodeIgniter Interview Questions and Answers for experienced

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100 CodeIgniter Interview Questions and Answers

  1. What is CodeIgniter?

    • Answer: CodeIgniter is a powerful PHP framework known for its elegance, simplicity, and speed. It's an open-source MVC (Model-View-Controller) framework that helps developers build dynamic websites quickly and easily. It's particularly well-suited for projects where rapid development is crucial.

  2. Explain the MVC architecture in CodeIgniter.

    • Answer: CodeIgniter follows the Model-View-Controller architectural pattern. The Model handles data interactions (database queries, etc.), the View displays the data to the user, and the Controller acts as an intermediary, managing the flow of data between the Model and the View. This separation of concerns promotes better organization, maintainability, and reusability of code.

  3. How do you handle database interactions in CodeIgniter?

    • Answer: CodeIgniter uses the Database class to interact with databases. You configure the database settings in the `config/database.php` file and then use the Active Record pattern or Query Builder to perform database operations like selecting, inserting, updating, and deleting data. It supports multiple database systems including MySQL, PostgreSQL, and others.

  4. What are CodeIgniter helpers and how are they used?

    • Answer: Helpers are collections of functions that provide common tasks like form creation, file uploading, URL manipulation, and more. They are loaded using the `$this->load->helper('helper_name');` line within your controller. Helpers reduce code duplication and improve organization.

  5. Explain CodeIgniter libraries.

    • Answer: Libraries are similar to helpers but offer more complex functionalities often involving class methods. They provide a structured way to implement reusable components. Examples include the Email library for sending emails and the Session library for managing user sessions.

  6. How do you handle form validation in CodeIgniter?

    • Answer: CodeIgniter's Form Validation library provides a robust way to validate user input. You define validation rules in your controller and use functions like `$this->form_validation->set_rules()` to specify the rules. The library then checks the input against those rules and provides error messages if needed.

  7. What are the different ways to load views in CodeIgniter?

    • Answer: You can load views using `$this->load->view('view_name');`. You can also pass data to the view using an associative array as the second argument. There's also `$this->load->view('view_name', $data, TRUE);` which returns the view's content instead of rendering it directly.

  8. How do you handle routing in CodeIgniter?

    • Answer: Routing is configured in the `config/routes.php` file. You can map URLs to specific controllers and methods. CodeIgniter provides default routing rules, but you can customize them to create user-friendly and SEO-friendly URLs.

  9. Explain CodeIgniter's autoloading capabilities.

    • Answer: CodeIgniter allows you to autoload helpers, libraries, and plugins. This is done by configuring the `autoload` array in the `config/autoload.php` file. Autoloading simplifies the process of including required files in your controllers.

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