php 验证码

<?php
session_start();
@header("Content-Type:image/png");    //设置header格式为png格式
$str = "1,2,3,4,5,6,7,8,9,a,b,c,d,f,g"; 
$list = explode(",", $str);
$cmax = count($list) - 1;
$verifyCode = '';
for ( $i=0; $i < 5; $i++ ){
      $randnum = mt_rand(0, $cmax);
      $verifyCode .= $list[$randnum];      
}
$_SESSION['code'] = $verifyCode; 
 
$Code = $_SESSION['code'];      //页面传递过来的随机验证码
$width = 191;          //验证码图片的宽度
$height = 68;          //验证码图片的高度
$img=imagecreate($width,$height);
$back=imagecolorallocate($img,0xFF,0xFF,0xFF); //背景色
$pix=imagecolorallocate($img,187,230,247);  //模糊点颜色
$fontColor=imagecolorallocate($img,41,163,238); //字体色
$fontType='C:\Windows\Fonts\simhei.ttf';  //设置字体样式，这里是黑体
mt_srand(); 
         //绘模糊作用的点
for($i=0;$i<1000;$i++)
{
 imagesetpixel($img,mt_rand(0,$width),mt_rand(0,$height),$pix);
}
imagettftext($img, 35, 0, 25, 52, $fontColor, $fontType, $Code);
imagerectangle($img,0,0,$width-1,$height-1,$fontColor);
imagepng($img);
imagedestroy($img);
?>

<img id="code"  src="master/inc/create_code.php"  width="80" height="22" onClick="this.src=this.src + '?Math.random()*10000';"  />