PHP几个比较常见的面试程序题整理

反转字符串可以使用【strrev】但是最终要的就是多字节字符串

//反转字符串function mb_strrev($str){$len = mb_strlen($str,'utf-8');$r = array();for($i=0;$i<$len;$i++){$r[] = mb_substr($str,$i,1,'utf-8');}return implode(array_reverse($r));}

得到URL中扩展名，注意URL中不一定有扩展名的

//得到url中扩展名function getUrlExt($str){$url_info = parse_url($str);if(array_key_exists('path',$url_info)){$path = $url_info['path'];$file_info = pathinfo($path);if(array_key_exists('extension',$file_info)){return $file_info['extension'];}}return false;}

计算两个文件的相对路径

function get_rela_path($file_1,$file_2){$array_1 = explode($file_1);$array_2 = explode($file_2);$rela = array_intersect_assoc($array_1,$array_2);$length = count($rela);if(count($array_2)-$length-1 == 0){$a_r = array_fill(0,1,'.');}else{$a_r = array_fill(0,count($array_2)-$length-1,'..');}$b_r = array_slice($array_2,$length);$a_res = array_merge($a_r,$b_r);$str_res = implode('/',$a_res);return $str_res;}