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<5;$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<50;$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);

header("Cache-Control: max-age=1, s-maxage=1, no-cache, must-revalidate");

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

imagepng($im);

imagedestroy($im);

}

?>