ottenere title pagina con php

[francy88]

questo funziona in parte:

$file = file("http://www.pippo.it"); 
$file = implode("",$file);  
if(preg_match("/<title>(.+)<\/title>/i",$file,$m)){
print "The title of $url is [b]$m[1]";} 
else{ print "The page doesn't have a title tag";} 

pero' io vorrei passare un url dinamicamente tramite variabile, cosi:

$file = file($url); 
$file = implode("",$file);  
if(preg_match("/<title>(.+)<\/title>/i",$file,$m)){
print "The title of $url is [b]$m[1]";} 
else{ print "The page doesn't have a title tag";} 

pero' non funziona...come mai?