PHP code sharing for finding and replacing http addresses in strings

<?php
/**
* 查找、替换字符串http地址
* edit by bbs.it-home.org
*/
function convertImg($str)  
{  
   $str = preg_replace("/\{([^}]+)\}/",'<div style="border:1px dashed #003366; 
background-color:#f0f0f0; height:21px; color:#003399">回复：$1</div>',preg_replace("/\[(\d+)\]/",
'<img  src="/images/face/face$1.jpg"/ alt="PHP code sharing for finding and replacing http addresses in strings" >',$str));  
   $reg="/http\:\/\/(\w+\.)+(net|com|org|cn|kr|jp|tw)[A-Za-z0-9_&\/\?=]*/i";  
   if(preg_match_all($reg,$str,$out))  
   {  
   for($i=0;$i<count($out[0]);$i++)  
   {  
     $link=substr(base64_encode(md5(preg_replace("/http\:\/\//","",$out[0][$i]))),0,10+strlen($str)%10);  
     $str=str_replace($out[0][$i],'http://'.$link.'',$str);
}  
}  
return $str;  
}
?>