PHP验证码函数代码(简单实用)

效果图：

复制代码代码如下:

/**
* vCode(m,n,x,y) m个数字 显示大小为n 边宽x 边高y
* micxp
*jb51.net
*/
session_start();
vCode(4, 15); //4个数字，显示大小为15

function vCode($num = 4, $size = 20, $width = 0, $height = 0) {
!$width && $width = $num * $size * 4 / 5 + 5;
!$height && $height = $size + 10;
// 去掉了 0 1 O l 等
$str = "23456789abcdefghijkmnpqrstuvwxyzABCDEFGHIJKLMNPQRSTUVW";
$code = '';
for ($i = 0; $i $code .= $str[mt_rand(0, strlen($str)-1)];
}
// 画图像
$im = imagecreatetruecolor($width, $height);
// 定义要用到的颜色
$back_color = imagecolorallocate($im, 235, 236, 237);
$boer_color = imagecolorallocate($im, 118, 151, 199);
$text_color = imagecolorallocate($im, mt_rand(0, 200), mt_rand(0, 120), mt_rand(0, 120));
// 画背景
imagefilledrectangle($im, 0, 0, $width, $height, $back_color);
// 画边框
imagerectangle($im, 0, 0, $width-1, $height-1, $boer_color);
// 画干扰线
for($i = 0;$i $font_color = imagecolorallocate($im, mt_rand(0, 255), mt_rand(0, 255), mt_rand(0, 255));
imagearc($im, mt_rand(- $width, $width), mt_rand(- $height, $height), mt_rand(30, $width * 2), mt_rand(20, $height * 2), mt_rand(0, 360), mt_rand(0, 360), $font_color);
}
// 画干扰点
for($i = 0;$i $font_color = imagecolorallocate($im, mt_rand(0, 255), mt_rand(0, 255), mt_rand(0, 255));
imagesetpixel($im, mt_rand(0, $width), mt_rand(0, $height), $font_color);
}
// 画验证码
@imagefttext($im, $size , 0, 5, $size + 3, $text_color, 'c:\\WINDOWS\\Fonts\\simsun.ttc', $code);
$_SESSION["VerifyCode"]=$code;
header("Cache-Control: max-age=1, s-maxage=1, no-cache, must-revalidate");
header("Content-type: image/png;charset=gb2312");
imagepng($im);
imagedestroy($im);
}
?>