摘要：
<?php//方法一:function extend_1($file_name){$retval="";$pt=strrpos($file_name, ".");if ($pt) $retval=substr($file_name, $pt+1, strlen($file_name) - $pt);return ($retval);}//方法二function extend_2($file_name){$extend = pathinfo($file_name);$extend = strtolower($extend["extensio 阅读全文