$data = file_get_contents("https://google.com/");
//if(preg_match('#<header>(.*?)</header>#',str_replace(["\n","\r"], "", $data),$header)){
if(preg_match('#<header class="header">(.*?)</header>#',str_replace(["\n","\r"], "", $data),$header)){
    echo $header[1];
}