Helper Functions
Helpers, as the name suggests, help you with tasks. Each helper file is simply a collection of functions in a particular category. There are URL Helpers, that assist in creating links, there are Form Helpers that help you create form elements, Text Helpers perform various text formatting routines, Cookie Helpers set and read cookies, File Helpers help you deal with files, etc.
Unlike most other systems in Code Igniter, Helpers are not written in an Object Oriented format. They are simple, procedural functions. Each helper function performs one specific task, with no dependence on other functions.
Helpers are intentionally kept very simple so that they can be used within your View Files with a minimal amount of code. This is important if you intend to have designers or non-programmer will be working with your view files, since it keeps the code to a minimum.
Code Igniter does not load Helper Files by default, so the first step in using a Helper is to load it. Once loaded, it becomes globally available in your controller and views.
Loading a Helper
Loading a helper file is quite simple using the following function:
$this->load->helper('name');
Where name is the file name of the helper, without the .php file extension or the "helper" part.
For example, to load the URL Helper file, which is named url_helper.php, you would do this:
$this->load->helper('url');
A helper can be loaded anywhere within your controller functions (or even within your View files, although that's not a good practice), as long as you load it before you use it. You can load your helpers in your controller constructor so that they become available automatically in any function, or you can load a helper in a specific function that needs it.
Note: The Helper loading function above does not return a value, so don't try to assign it to a variable. Just use it as shown.
Auto-loading Helpers
If you find that you need a particular helper globally throughout your application, you can tell Code Igniter to auto-load it during system initialization. This is done by opening the application/config/autoload.php file and adding the helper to the autoload array.
Using a Helper
Once you've loaded the Helper File containing the function you intend to use, you'll call it the way you would a standard PHP function.
For example, to create a link using the anchor() function in one of your view files you would do this:
<?=anchor('blog/comments', 'Click Here');?>
Where "Click Here" is the name of the link, and "blog/comments" is the URI to the controller/function you wish to link to.
Now What?
In the Table of Contents you'll find a list of all the available Helper Files. Browse each one to see what they do.