CodeIgniter Home
- What is CodeIgniter?
- Features of CodeIgniter
- Advantages over other PHP frameworks
- CodeIgniter version history
CodeIgniter Overview
- Key Components of CodeIgniter
- MVC design pattern explained
- Workflow of a CodeIgniter application
- System and Application folders overview
CodeIgniter Installing CodeIgniter
- System Requirements (PHP, MySQL, Extensions)
- Downloading & Extracting CodeIgniter
- Folder structure explained
- Setting base URL
- Configuring index.php file
- Running first application
CodeIgniter Application Architecture
- Folder structure in detail
- Application vs System folders
- Config, Controllers, Models, Views
- Helpers and Libraries placement
- User Guide access
CodeIgniter MVC Framework
- Understanding MVC flow
- Codeigniter Creating Controllers
- Creating Views
- Creating Models
- Loading Models and Views
- Data flow between MVC components
CodeIgniter Basic Concepts
- URLs in CodeIgniter
- Default controller setup
- Routing basics
- Auto-loading resources
- Naming conventions
CodeIgniter Configuration
- Configuration files overview
- Base URL and Index page settings
- Encryption key setup
- Codeigniter Database configuration
- Error logging configuration
- Custom configuration files
CodeIgniter Working with Database
- Database configuration
- Loading database library
- Query Builder class
- Running queries (select, insert, update, delete)
- Active Record class
- Transactions
- Joins, Grouping, Ordering, Limit
- Query bindings
- Result handling (row(), result())
CodeIgniter Libraries
- Built-in libraries overview
- Loading libraries
- Common libraries: Pagination, Upload, Email, Form Validation, Session, Encryption, Calendar
- Creating custom libraries
CodeIgniter Error Handling
- Error reporting levels
- Custom error pages (404, 500)
- Using log_message()
- Displaying errors in development vs production
CodeIgniter File Uploading
- Upload library setup
- File upload configuration (path, allowed types, max size)
- Handling errors in upload
- Multiple file uploads
- Securing uploads
CodeIgniter Sending Email
- Email library configuration
- Sending emails via SMTP
- Sending attachments
- Sending HTML emails
- Debugging email errors
CodeIgniter Form Validation
- Form validation library overview
- Setting validation rules
- Prepping data before validation
- Error messages customization
- Validation callbacks
- Server-side vs Client-side validation
CodeIgniter Session Management
- Session library configuration
- Storing session data
- Retrieving session data
- Flashdata in sessions
- Database-driven sessions
CodeIgniter Flashdata
- What is Flashdata?
- Creating flashdata messages
- Retrieving flashdata
- Flashdata expiration
CodeIgniter Tempdata
- Difference between flashdata & tempdata
- Creating tempdata
- Retrieving tempdata
- Removing tempdata
CodeIgniter Cookie Management
- Setting cookies
- Retrieving cookies
- Deleting cookies
- Cookie security
CodeIgniter Common Functions
- base_url()
- site_url()
- redirect()
- form_open() & form helper functions
- String helper functions
CodeIgniter Page Caching
- Enabling page caching
- Cache expiration
- Deleting cache files
- Best practices in caching
CodeIgniter Page Redirection
- Redirect helper function
- Permanent vs Temporary redirection
- Redirect with flashdata
CodeIgniter Application Profiling
- Enabling profiler
- Profiler sections (benchmarks, queries, post data, etc.)
- Customizing profiler output
CodeIgniter Benchmarking
- Benchmark class usage
- Measuring script execution time
- Measuring memory usage
- Custom benchmarks
CodeIgniter Adding JS and CSS
- Loading assets in views
- Using base_url() for assets
- Best practices for assets organization
- Versioning assets
CodeIgniter Internationalization
- Language files in CodeIgniter
- Loading language files
- Switching languages dynamically
- Multi-language website structure
CodeIgniter Security
- Input filtering and XSS cleaning
- CSRF protection
- SQL Injection prevention
- Password hashing & encryption
- Secure file uploads
- Using HTTPS with CodeIgniter

Running first application

Last modified on: September 7, 2025

<h1 data-start="486" data-end="535">📝 Running Your First CodeIgniter Application</h1>
<h2 data-start="537" data-end="557">🔎 Introduction</h2>
<p data-start="558" data-end="825">Once you&rsquo;ve installed and configured CodeIgniter, the next step is to <strong data-start="628" data-end="661">create your first application</strong>. By default, CodeIgniter comes with a sample <strong data-start="707" data-end="723">Welcome page</strong>. In this tutorial, we&rsquo;ll create a simple <strong data-start="765" data-end="792">Hello World application</strong> using a Controller and a View.</p>
<hr data-start="827" data-end="830" />
<h2 data-start="832" data-end="871">⚙️ 1. Start the Development Server</h2>
<h3 data-start="873" data-end="895">🔹 CodeIgniter 4</h3>
<p data-start="896" data-end="926">Run the built-in PHP server:</p>
<div class="contain-inline-size rounded-2xl relative bg-token-sidebar-surface-primary">
<div class="sticky top-9">
<div class="absolute end-0 bottom-0 flex h-9 items-center pe-2">
<div class="bg-token-bg-elevated-secondary text-token-text-secondary flex items-center gap-4 rounded-sm px-2 font-sans text-xs">
<pre class="language-php"><code>php spark serve
</code></pre>
</div>
</div>
</div>
</div>
<p data-start="955" data-end="963">Visit:</p>
<div class="contain-inline-size rounded-2xl relative bg-token-sidebar-surface-primary">
<div class="sticky top-9">
<div class="absolute end-0 bottom-0 flex h-9 items-center pe-2">
<div class="bg-token-bg-elevated-secondary text-token-text-secondary flex items-center gap-4 rounded-sm px-2 font-sans text-xs">
<pre class="language-php"><code>http://localhost:8080/
</code></pre>
</div>
</div>
</div>
</div>
<p data-start="995" data-end="1048">👉 You should see the <strong data-start="1017" data-end="1045">CodeIgniter Welcome Page</strong>.</p>
<h3 data-start="1050" data-end="1072">🔹 CodeIgniter 3</h3>
<p data-start="1073" data-end="1112">If using XAMPP/WAMP/MAMP, just visit:</p>
<div class="contain-inline-size rounded-2xl relative bg-token-sidebar-surface-primary">
<div class="sticky top-9">
<div class="absolute end-0 bottom-0 flex h-9 items-center pe-2">
<div class="bg-token-bg-elevated-secondary text-token-text-secondary flex items-center gap-4 rounded-sm px-2 font-sans text-xs">
<pre class="language-php"><code>http://localhost/codeigniter-app/
</code></pre>
</div>
</div>
</div>
</div>
<hr data-start="1156" data-end="1159" />
<h2 data-start="1161" data-end="1200">📂 2. Create Your First Controller</h2>
<h3 data-start="1202" data-end="1261">CodeIgniter 4 (Controllers inside <code data-start="1240" data-end="1258">app/Controllers/</code>)</h3>
<ol data-start="1262" data-end="1344">
<li data-start="1262" data-end="1292">
<p data-start="1265" data-end="1292">Go to <code data-start="1271" data-end="1289">app/Controllers/</code>.</p>
</li>
<li data-start="1293" data-end="1324">
<p data-start="1296" data-end="1324">Create a file <code data-start="1310" data-end="1321">Hello.php</code>.</p>
</li>
<li data-start="1325" data-end="1344">
<p data-start="1328" data-end="1344">Add this code:</p>
</li>
</ol>
<div class="contain-inline-size rounded-2xl relative bg-token-sidebar-surface-primary">
<div class="sticky top-9">
<div class="absolute end-0 bottom-0 flex h-9 items-center pe-2">
<div class="bg-token-bg-elevated-secondary text-token-text-secondary flex items-center gap-4 rounded-sm px-2 font-sans text-xs">
<pre class="language-php"><code>&lt;?php 
namespace App\Controllers;

class Hello extends BaseController
{
    public function index()
    {
        return view('hello_view');
    }
}
</code></pre>
</div>
</div>
</div>
</div>
<hr data-start="1507" data-end="1510" />
<h3 data-start="1512" data-end="1579">CodeIgniter 3 (Controllers inside <code data-start="1550" data-end="1576">application/controllers/</code>)</h3>
<ol data-start="1580" data-end="1670">
<li data-start="1580" data-end="1618">
<p data-start="1583" data-end="1618">Go to <code data-start="1589" data-end="1615">application/controllers/</code>.</p>
</li>
<li data-start="1619" data-end="1650">
<p data-start="1622" data-end="1650">Create a file <code data-start="1636" data-end="1647">Hello.php</code>.</p>
</li>
<li data-start="1651" data-end="1670">
<p data-start="1654" data-end="1670">Add this code:</p>
</li>
</ol>
<div class="contain-inline-size rounded-2xl relative bg-token-sidebar-surface-primary">
<div class="sticky top-9">
<div class="absolute end-0 bottom-0 flex h-9 items-center pe-2">
<div class="bg-token-bg-elevated-secondary text-token-text-secondary flex items-center gap-4 rounded-sm px-2 font-sans text-xs">
<pre class="language-php"><code>&lt;?php
defined('BASEPATH') OR exit('No direct script access allowed');

class Hello extends CI_Controller {

public function index()
    {
        $this-&gt;load-&gt;view('hello_view');
    }
}
</code></pre>
</div>
</div>
</div>
</div>
<hr data-start="1875" data-end="1878" />
<h2 data-start="1880" data-end="1913">📄 3. Create Your First View</h2>
<h3 data-start="1915" data-end="1963">CodeIgniter 4 &rarr; <code data-start="1935" data-end="1961">app/Views/hello_view.php</code></h3>
<h3 data-start="1964" data-end="2020">CodeIgniter 3 &rarr; <code data-start="1984" data-end="2018">application/views/hello_view.php</code></h3>
<p data-start="2022" data-end="2038">Add this code:</p>
<div class="contain-inline-size rounded-2xl relative bg-token-sidebar-surface-primary">
<div class="sticky top-9">
<div class="absolute end-0 bottom-0 flex h-9 items-center pe-2">
<div class="bg-token-bg-elevated-secondary text-token-text-secondary flex items-center gap-4 rounded-sm px-2 font-sans text-xs">
<pre class="language-php"><code>&lt;!DOCTYPE html&gt;
&lt;html&gt;
&lt;head&gt;
    &lt;title&gt;Hello World in CodeIgniter&lt;/title&gt;
&lt;/head&gt;
&lt;body&gt;
    &lt;h1&gt;&lt;?php echo "Hello, CodeIgniter! 🚀"; ?&gt;&lt;/h1&gt;
&lt;/body&gt;
&lt;/html&gt;
</code></pre>
</div>
</div>
</div>
</div>
<hr data-start="2211" data-end="2214" />
<h2 data-start="2216" data-end="2250">🌐 4. Access Your Application</h2>
<ul data-start="2252" data-end="2410">
<li data-start="2252" data-end="2320">
<p data-start="2254" data-end="2278">For <strong data-start="2258" data-end="2275">CodeIgniter 4</strong>:</p>
<div class="contain-inline-size rounded-2xl relative bg-token-sidebar-surface-primary">
<div class="sticky top-9">
<div class="absolute end-0 bottom-0 flex h-9 items-center pe-2">
<div class="bg-token-bg-elevated-secondary text-token-text-secondary flex items-center gap-4 rounded-sm px-2 font-sans text-xs">
<pre class="language-php"><code>http://localhost:8080/hello
</code></pre>
</div>
</div>
</div>
</div>
</li>
<li data-start="2321" data-end="2410">
<p data-start="2323" data-end="2347">For <strong data-start="2327" data-end="2344">CodeIgniter 3</strong>:</p>
<div class="contain-inline-size rounded-2xl relative bg-token-sidebar-surface-primary">
<div class="sticky top-9">
<div class="absolute end-0 bottom-0 flex h-9 items-center pe-2">
<div class="bg-token-bg-elevated-secondary text-token-text-secondary flex items-center gap-4 rounded-sm px-2 font-sans text-xs">
<pre class="language-php"><code>http://localhost/codeigniter-app/index.php/hello
</code></pre>
</div>
</div>
</div>
</div>
</li>
</ul>
<p data-start="2411" data-end="2488">👉 If you have removed <code data-start="2434" data-end="2445">index.php</code> using <code data-start="2452" data-end="2463">.htaccess</code>, you can simply visit:</p>
<div class="contain-inline-size rounded-2xl relative bg-token-sidebar-surface-primary">
<div class="sticky top-9">
<div class="absolute end-0 bottom-0 flex h-9 items-center pe-2">
<div class="bg-token-bg-elevated-secondary text-token-text-secondary flex items-center gap-4 rounded-sm px-2 font-sans text-xs">
<pre class="language-php"><code>http://localhost/codeigniter-app/hello
</code></pre>
</div>
</div>
</div>
</div>
<hr data-start="2537" data-end="2540" />
<h2 data-start="2542" data-end="2555">✅ Output</h2>
<p data-start="2557" data-end="2570">You&rsquo;ll see:</p>
<div class="contain-inline-size rounded-2xl relative bg-token-sidebar-surface-primary">
<div class="sticky top-9">
<div class="absolute end-0 bottom-0 flex h-9 items-center pe-2">
<div class="bg-token-bg-elevated-secondary text-token-text-secondary flex items-center gap-4 rounded-sm px-2 font-sans text-xs">
<pre class="language-php"><code>Hello, CodeIgniter! 🚀
</code></pre>
</div>
</div>
</div>
</div>
<p data-start="2604" data-end="2685">🎉 Congratulations! You&rsquo;ve successfully run your first CodeIgniter application.</p>
<hr data-start="2687" data-end="2690" />
<h2 data-start="2692" data-end="2710">🎯 Conclusion</h2>
<p data-start="2711" data-end="2768">Running your first application in CodeIgniter involves:</p>
<ol data-start="2769" data-end="2905">
<li data-start="2769" data-end="2816">
<p data-start="2772" data-end="2816">Starting the server (or using XAMPP/WAMP).</p>
</li>
<li data-start="2817" data-end="2848">
<p data-start="2820" data-end="2848">Creating a <strong data-start="2831" data-end="2845">Controller</strong>.</p>
</li>
<li data-start="2849" data-end="2874">
<p data-start="2852" data-end="2874">Creating a <strong data-start="2863" data-end="2871">View</strong>.</p>
</li>
<li data-start="2875" data-end="2905">
<p data-start="2878" data-end="2905">Accessing it via browser.</p>
</li>
</ol>
<p data-start="2907" data-end="3041">This forms the foundation of the <strong data-start="2940" data-end="2957">MVC framework</strong>, where Controllers handle requests, Models manage data, and Views display output.</p>

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