php - Warning: preg_match(): Unknown modifier ' ' in -

I do not understand what's wrong, how can I get this error for this simple regex. I can type whatever I want, it will always give me the same error and in the message itself does not show which correctional problem causes, modifier is just empty.

  public function getRows ($ content) {$ regex = '/ [az] + /'; Preg_match ($ content, $ regex, $ lines); Print_r ($ lines); Go out; Return refund;    
 
 
 
 
  first  parameter is regex , Em> second  is the subject:  
 
 int preg_match (string $ pattern, string $ theme ...   
  to < / Sup>  
 Therefore it should work fine:  
  preg_match ($ regex, $ content, $ rows);