In recent years, the advancement of Web development technology and the continuous expansion of global Internet applications have made PHP technology more and more widely used. As a rapidly developing technology, its ecosystem continues to grow. Among them, CodeIgniter, as one of the famous frameworks in the field of PHP development, is very popular among many developers. This article will introduce the relevant knowledge of the CodeIgniter framework to provide an introductory guide for beginners.

1. What is the CodeIgniter framework?

CodeIgniter, also known as CI, is a lightweight PHP framework using the MVC design pattern. It provides a simple way to create web applications, reducing the amount and complexity of developer code. The CodeIgniter framework was developed by EllisLab using PHP scripting language and is an open source software. The current latest version of CodeIgniter is 3.1.11, released in 2020.

The CodeIgniter framework is known for its flexibility and simplicity, with powerful libraries and helper classes and a rich set of configuration options. It provides the tools needed to quickly develop websites, but maintains a clean coding structure to help developers maintain and collaborate. In addition, CodeIgniter also supports a variety of databases, including MySQL, PostgreSQL, SQLite, Oracle, etc.

2. How to install the CodeIgniter framework?

The installation of the CodeIgniter framework is extremely simple. You can install it by following the steps below:

1. Go to the official website https://codeigniter.com/

2. Click the download button in the upper right corner of the page to download the latest version of CodeIgniter.

3. Unzip the zip file into your web server, such as http://localhost/myproject/codeigniter/.

At this point, the installation process has been completed. Next, you can create the first controller of your CodeIgniter application to verify that your installation was successful.

3. How to create the first CodeIgniter application?

Now, let’s demonstrate how to create a simple CodeIgniter application. Next, we'll start with a simple controller file to give you an idea of ??how this framework works.

1. Enter the configuration file application/config/config.php of the CodeIgniter framework and set your base URL to:

$config['base_url'] = 'http:// localhost/myproject/codeigniter/';

2. Next, create a new controller file named Myclass.php. Then, copy and paste the following code into the Myclass.php file. Please make sure to save this file under the path application/controllers/.

defined('BASEPATH') OR exit('No direct script access allowed');

class Myclass extends CI_Controller {

public function index()
{
    echo 'Welcome to CodeIgniter!';
}

}

3. At this point, our first CodeIgniter application is complete, and then we need to access your new controller through the browser. Enter the following URL: http://localhost/myproject/codeigniter/index.php/myclass. If everything is normal, the page will display the message "Welcome to CodeIgniter!"

4. Core features of the CodeIgniter framework

1. Loose coupling: CodeIgniter tries to organize the code in a loosely coupled way as much as possible to improve the maintainability and reliability of the program. Scalability.

2. Model-Controller-View (MVC) architecture: CodeIgniter adopts the MVC design pattern to separate logic, data and presentation, making the program simpler and easier to expand to a certain extent.

3. Library and Helper: CodeIgniter comes with a large number of libraries and helpers that can quickly complete complex tasks, such as image processing, form validation, string processing, etc.

4. Security: CodeIgniter implements multiple security features in the application, including password hashing, input data filtering, CSRF protection, etc.

5. DB extension: CodeIgniter can easily connect to different databases, including MySQL, PostgreSQL, SQLite, Oracle and other common relational databases.

5. Summary

CodeIgniter is a flexible and powerful framework that provides PHP developers with an easy way to build web applications. I believe that through the introduction of this article, readers will have a deeper understanding of the CodeIgniter framework. CodeIgniter has a low learning threshold, and beginners can quickly master its basic usage through practical operations. In future development, you may wish to try using CodeIgniter to simplify development work and improve development efficiency.

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