<?php #这不是抽奖程序的源代码！不许看！ header("Content-Type: text/html;charset=utf-8"); session_start(); if(!isset($_SESSION['seed'])){ $_SESSION['seed']=rand(0,999999999);  //设置session为随机种子} 

mt_srand($_SESSION['seed']);  //播种Mersenne Twister 随机数生成器

$str_long1 = "abcdefghijklmnopqrstuvwxyz0123456789ABCDEFGHIJKLMNOPQRSTUVWXYZ"; $str=''; $len1=20;  //长度为20for ( $i = 0; $i < $len1; $i++ ){     $str.=substr($str_long1, mt_rand(0, strlen($str_long1) - 1), 1);        } //mt_rand :使用 Mersenne Twister 算法返回随机整数。$str_show = substr($str, 0, 10); //只显示前十个字符，substring字符串截取函数echo "<p id='p1'>".$str_show."</p>"; 

if(isset($_POST['num'])){  //传一个num过去，完整的str    if($_POST['num']===$str){x         echo "<p id=flag>抽奖，就是那么枯燥且无味，给你flag{xxxxxxxxx}</p>";     }     else{         echo "<p id=flag>没抽中哦，再试试吧</p>";     } } show_source("check.php");