title: how sanitize input codeigniter 3?
body: <p>First of all I should remind you that I have read <a href="https://stackoverflow.com/questions/14757812/codeigniter-best-practice-to-sanitize-input">this post</a> and few other posts about my question but most of all are almost old and they are for about 3 years ago.</p>
  
  <p>Now I'm using CodeIgniter 3 and I want to know what's the best sanitize filter for my data which I'm retrieving them from users before insert into database.</p>
  
  <p>This is for my website to register and and I don't know what kind of user is registering and I can't trust them. And it is possible that it will be dangerous I want to  sanitize  all input before inserting it into database I don't know <code>input</code> class enough for sanitizing it ?<br>
  Please tell me the codeigniter sanitizing  functions ! </p>
  
  <p>I have read security classs in codeigniter document, but I want to be sure.</p>