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/*=====================
产生随机字符串函数
=====================*/
function random($length) {
$hash = '';
$chars = 'abcdefghijklmnopqrstuvwxyz0123456789abcdefghijklmnopqrstuvwxyz';
$max = strlen($chars) - 1;
mt_srand((double)microtime() * 1000000);
for($i = 0; $i < $length; $i++) {
$hash .= $chars[mt_rand(0, $max)];
}
return $hash;
}
//验证码图片生成
session_start();
//通知浏览器将要输出png图片
header("content-type: image/png");
//准备好随机数发生器种子
//srand((double)microtime()*1000000);
//准备图片的相关参数
$im = imagecreate(62,22);
$black = imagecolorallocate($im, 0,0,0); //rgb黑色标识符
$white = imagecolorallocate($im, 255,255,255); //rgb白色标识符
$gray = imagecolorallocate($im, 179,183,185); //rgb灰色标识符
//开始作图
imagefill($im,0,0,$gray);
//while(($randval=rand()%100000)<10000);{
//$_session["check_code"] = $randval;
//将四位整数验证码绘入图片
$randval=random(4);
$_session["check_code"]=$randval;
imagestring($im, 5, 10, 3, $randval, $white);
//}
//加入干扰象素
for($i=0;$i<150;$i++){
$randcolor = imagecolorallocate($im,rand(0,255),rand(0,255),rand(0,255));
imagesetpixel($im, rand()%70 , rand()%30 , $white);
}
//输出验证图片
imagepng($im);
//销毁图像标识符
imagedestroy($im);
?>
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