[Solved] Compressing a string PHP [closed]

function line_encoding($e){
    $s = preg_split("//",$e);
    $s[-1] = "";
    $o = 1;
    $f = "";
    for($c=0;$c<strlen($e);$c++){
        if($s[$c]==$s[$c-1]){
            $o++;
        }else{
            $f .= $o==1?$s[$c-1]:($o.$s[$c-1]);
            $o=1;
        }
    }
    return $f;
}

Check if this works