/*** 5种方式获取文件后缀名* 这道题其实就是考函数substr() strrchr()  array_pop()  strrpos() strpos() strrev() explode()  pathinfo()* @param string $filename 要处理的文件名  1.jpg/1.png/1.html/1.php* @return string .php/php  */function get_ext1($filename){        return strrchr($filename,'.');}function get_ext2($filename){        return substr($filename,strrpos($filename,'.'));}function get_ext3($filename){        return array_pop(explode('.',$filename));}function get_ext4($filename){        return pathinfo($filename,PATHINFO_EXTENSION);}function get_ext5($filename){        return strrev(substr(strrev($filename),0,strpos(strrev($filename),'.')));}$filename = "1.php";echo get_ext1($filename)."n";echo get_ext2($filename)."n";echo get_ext3($filename)."n";echo get_ext4($filename)."n";echo get_ext5($filename)."n";

/*** 遍历目录(递归)* @param string $dir 目录名且最后没有/* @return array $files 整个目录结构*/function myScandir($dir){        $files = array();        if($handle = opendir($dir)){                while (($file = readdir($handle)) != false){                        if($file != "." && $file != ".."){                                $newDir = $dir."/".$file;                                if(is_dir($newDir)){                                        $files[$file] = myScandir($newDir);                                }else{                                        $files[] = $file;                                }                        }                }                closedir($handle);                return $files;        }}$dir = "/dirname";print_r(myScandir($dir));