最简单的php验证码代码

 1 show.php
 2 
 3  <?php
 4     session_start();
 5     if($_POST[check]){
 6         
 7         if($_POST[check]==$_SESSION[check_pic]){
 8             echo "验证码正确".$_SESSION[check_pic];
 9         }
10         else {
11             echo "验证码错误".$_SESSION[check_pic];
12         }
13     }
14     
15     
16  ?>
17  <form action="" method="post">
18  <img src="checkTest.php" /><br />
19  <input name="check" type="text" /><br />
20 <input name="" type="submit" value="提交"/>
21 </form>




check.php

<?php

session_start();
for($i=0;$i<4;$i++)
     {
$rand.= dechex(rand(1, 15));

     }
$_SESSION[check_pic]=$rand;

$im=imagecreatetruecolor(100, 30);

//set color
     $bg=imagecolorallocate($im, 0, 0,0);//background color
     $te=imagecolorallocate($im, 255, 255, 255);

for($i=0;$i<3;$i++){    
$te2=imagecolorallocate($im, rand(0,255), rand(0,255), rand(0,255));
//set line
     imageline($im, rand(0,100), 0, 100, 30, $te2);
     }
for($i=0;$i<200;$i++){
         imagesetpixel($im, rand()%100, rand()%30, $te2);

     }

$str=iconv("gbk", "UTF-8", "显示UTF-8");
     imagettftext($im, 14,9,20,20,$te,\'CHILLER.TTF\', $str);

//
    //imagestring($im, rand(1, 6),rand(3, 70), rand(0, 15), $rand, $te);

    //show 
    header("Content-type:image/jpeg");
    imagejpeg($im);


?>



show.php