php中将网址转换为超链接的函数

functionshowtext($text){
$search=array("|(http://[^]+)|","|(https://[^]+)|","|(www.[^]+)|");
$replace=array("<ahref="$1"target="_blank">$1</a>","<ahref="$1"target="_blank">$1</a>","<ahref="http://$1"target="_blank">$1</a>");
$text=preg_replace($search,$replace,$text);
return$text;
}