复制代码 代码如下:

<?php

//-------------------------------------

// 文件说明：数学运算验证码

// 文件作者：Jesse Lee

// 最后更新：2008-09-07

//-------------------------------------

session_start();

$sessionvar = 'vdcode'; //Session变量名称

$width = 150; //图像宽度

$height = 20; //图像高度

$operator = '+-*'; //运算符

$code = array();

$code[] = mt_rand(1,9);

$code[] = $operator{mt_rand(0,2)};

$code[] = mt_rand(1,9);

$code[] = $operator{mt_rand(0,2)};

$code[] = mt_rand(1,9);

$codestr = implode('',$code);

eval("$result = ".implode('',$code).";");

$code[] = '=';

$_SESSION[$sessionvar] = $result;

$img = ImageCreate($width,$height);

ImageColorAllocate($img, mt_rand(230,250), mt_rand(230,250), mt_rand(230,250));

$color = ImageColorAllocate($img, 0, 0, 0);

$offset = 0;

foreach ($code as $char) {

$offset += 20;

$txtcolor = ImageColorAllocate($img, mt_rand(0,255), mt_rand(0,150), mt_rand(0,255));

ImageChar($img, mt_rand(3,5), $offset, mt_rand(1,5), $char, $txtcolor);

}

for ($i=0; $i<100; $i++) {

$pxcolor = ImageColorAllocate($img, mt_rand(0,255), mt_rand(0,255), mt_rand(0,255));

ImageSetPixel($img, mt_rand(0,$width), mt_rand(0,$height), $pxcolor);

}

header('Content-type: image/png');

ImagePng($img);

?>