Notice: Undefined index: extension in /var/www/.. on line 187
//185 - $f_name = $this->filename;
//186 - $path_parts = pathinfo($f_name);
//187 - $file_ext = $path_parts['extension'];
经过一些谷歌搜索后,我看到很多 Isset 被使用。但我很怀疑,在这种情况下如何使用它?它甚至可以解决问题吗?