Check a variable using regex

Question

Im about to create a registration form for my website. I need to check the variable, and accept it only if contains letter, number, _ or -.

How can do it with regex? I used to work with them with preg_replace(), but i think this is not the case. Also, i know that the "ereg" function is dead. Any solutions?

Answer 1

this regex is pretty common these days.

if(preg_match('/^[a-z0-9\-\_]+$/i',$username))
{
   // Ok
}