$temp_arr = explode(".", $file_name);
$file_ext = array_pop($temp_arr);
$file_ext = trim($file_ext);
$file_ext = strtolower($file_ext);
转自:https://blog.csdn.net/xuyaokun123/article/details/51816309
$temp_arr = explode(".", $file_name);
$file_ext = array_pop($temp_arr);
$file_ext = trim($file_ext);
$file_ext = strtolower($file_ext);
转自:https://blog.csdn.net/xuyaokun123/article/details/51816309