MY_Form_validation.php

<?php if (!defined('BASEPATH')) exit('No direct script access allowed.');
 
class MY_Form_validation extends CI_Form_validation {
 
  function MY_Form_validation() {
    parent::CI_Form_validation();
  }
  
  // matches_pattern()
  // Ensures a string matches a basic pattern
  // # numeric, ? alphabetical, ~ any character
  function matches_pattern($str, $pattern) {
    $characters = array(
      '#', '?', '~'
    );

    $regex_characters = array(
      '[0-9]', '[a-zA-Z]', '.'
    );

    $pattern = str_replace($characters, $regex_characters, $pattern);
    if (preg_match('/^' . $pattern . '$/', $str)) return TRUE;
    return FALSE;
  }
}