CodeIgniter - Common Functions

CodeIgniter library functions and helper functions need to be initialized before they are used but there are some common functions, which do not need to be initialized.

These common functions and their descriptions are given below.

Syntax is_php($version)

$version (string) − Version number

Return TRUE if the running PHP version is at least the one specified or FALSE if not
Return Type void
Description Determines if the PHP version being used is greater than the supplied version number.
Syntax is_really_writable($file)

$file (string) − File path

Return TRUE if the path is writable, FALSE if not
Return Type bool
Description checks to see if file is writable or not.
Syntax config_item($key)

$key (string) − Config item key

Return Configuration key value or NULL if not found
Return Type mixed
Description This function is used to get the configuration item
Syntax set_status_header($code[, $text = ''])

$code (int) − HTTP Response status code

$text (string) − A custom message to set with the status code

Return Type void
Description This function permits you to manually set a server status header.
Syntax remove_invisible_characters($str[, $url_encoded = TRUE])

$str (string) − Input string

$url_encoded (bool) − Whether to remove URLencoded characters as well

Return Sanitized string
Return Type string
Description This function prevents inserting NULL characters between ASCII characters
Syntax html_escape($var)

$var (mixed) − Variable to escape (string or array)

Return HTML escaped string(s)
Return Type mixed
Description This function acts as a native PHP htmlspecialchars() function.
Syntax get_mimes()
Return An associative array of file types
Return Type array
Description This function returns a reference to the MIMEs array from application/config/mimes.php.
Syntax is_https()
Return TRUE if currently using HTTP-over-SSL, FALSE if not
Return Type bool
Description Returns TRUE if a secure (HTTPS) connection is used and FALSE in any other case (including non-HTTP requests).
Syntax is_cli()
Return TRUE if currently running under CLI, FALSE otherwise
Return Type bool
Description Returns TRUE if the application is run through the command line and FALSE if not.
Syntax function_usable($function_name)

$function_name (string) − Function name

Return Type bool
Description Returns TRUE if a function exists and is usable, FALSE otherwise.

Given below is an example, which demonstrates all of the above functions.


Here we have created only one controller in which we will use the above functions. Copy the below given code and save it at application/controller/CommonFun_Controller.php.

   class CommonFun_Controller extends CI_Controller { 
      public function index() {
         echo is_php('5.3')."<br>"; 
         echo config_item('language')."<br>"; 
         echo remove_invisible_characters('This is a ‌test','UTF8')."<br>"; 
         $str = '< This > is \' a " test & string'; 
         echo html_escape($str)."<br>"; 
         echo "is_https():".var_dump(is_https())."<br>"; 
         echo "is_cli():".var_dump(is_cli())."<br>"; 
         echo "get_mimes():".print_r(get_mimes())."<br>"; 
      public function test() { 
         echo "Test function"; 

Change the routes.php file at application/config/routes.php to add route for the above controller and add the following line at the end of the file.

$route['commonfunctions'] = 'CommonFun_Controller';

Type the following URL in the address bar of your browser to execute the example.