<?php session_start(); $rn=mt_rand(); ?> <html> <title>blablabla</title> <body> <form method="POST"> 1: <input type="text" name="1" maxlength="5"/> <br/> 2: <input type="text" name="2" maxlength="5"/> <input type="hidden" name="randnum" value="<?=$rn ?>"> <br/> <br/> <input type="submit"/> </form> <?php $var1 = isset($_POST['1']) ? $_POST['1'] : ''; $var2 = isset($_POST['2']) ? $_POST['2'] : ''; $rn2=isset($_POST['randnum']) ? $_POST['randnum'] : ''; if(!isset($_SESSION['rnum']) || $_SESSION['rnum']!=$rn2) { if (!empty($var1) && !empty($var2)) echo '<textarea cols="35" rows="4">'.md5(md5($var1.$var2)).'</textarea>'; $_SESSION['rnum']=$rn2; } ?> </body> </html>