URL Friendly Username in PHP?

Question

On my PHP site, currently users login with an email address and a password. I would like to add a username as well, this username they g\set will be unique and they cannot change it. I am wondering how I can make this name have no spaces in it and work in a URL so I can use there username to link to there profiles and other stuff. If there is a space in there username then it should add an underscore jason_davis. I am not sure the best way to do this?

Answer 1

function Slug($string)
{
    // convert to entities
    $string = htmlentities( $string, ENT_QUOTES, 'UTF-8' );
    // regex to convert accented chars into their closest a-z ASCII equivelent
    $string = preg_replace( '~&([a-z]{1,2})(?:acute|cedil|circ|grave|lig|orn|ring|slash|th|tilde|uml);~i', '$1', $string );
    // convert back from entities
    $string = html_entity_decode( $string, ENT_QUOTES, 'UTF-8' );
    // any straggling caracters that are not strict alphanumeric are replaced with a dash
    $string = preg_replace( '~[^0-9a-z]+~i', '-', $string );
    // trim / cleanup / all lowercase
    $string = trim( $string, '-' );
    $string = strtolower( $string );
    return $string;
}

$user = 'Alix Axel';
echo Slug($user); // alix-axel

$user = 'Álix Ãxel';
echo Slug($user); // alix-axel

$user = 'Álix----_Ãxel!?!?';
echo Slug($user); // alix-axel