PHPのシンプルなクローラー

function get_urls($url)
 {
 $url_array=array();
 $the_first_content=file_get_contents($url);
 $the_second_content=file_get_contents($url);
 $pattern1 = "/http:// [a-zA-Z0-9.?/-=&:+-_'"]+/";
 $pattern2="/http://[a-zA-Z0-9.]+/";
 preg_match_all($pattern2, $the_first_content, $matches2);
 preg_match_all($pattern1, $the_first_content, $matches1);
 $new_array1=array_unique($matches1[0]);
 $new_array2=array_unique($matches2[0]) ;
 $final_array=array_merge($new_array1,$new_array2);
 $final_array=array_unique($final_array);
 for($i=0;$i {
 echo $final_array [$i]."";
 }
 }
 get_urls("http://www.baidu.com");