PHP验证码之数字运算验证码

<?php//如果对代码不理解请看我上一篇的详细解答。//数字验证码：http://my.oschina.net/u/2391943/blog/485163getValidate(100,30);function getValidate($w,$h){$img = imagecreate($w,$h);$gray = imagecolorallocate($img,255,255,255);$black = imagecolorallocate($img,rand(0,200),rand(0,200),rand(0,200));$red = imagecolorallocate($img, 255, 0, 0);$white = imagecolorallocate($img, 255, 255, 255);$green = imagecolorallocate($img, 0, 255, 0);$blue = imagecolorallocate($img, 0, 0, 255);imagefilledrectangle($img, 0, 0, 100, 30, $black);for($i = 0;$i < 80;$i++){imagesetpixel($img, rand(0,$w), rand(0,$h), $gray);}$num1 = rand(1,99);$num2 = rand(1,99);imagestring($img, 5, 5, rand(1,10), $num1, $red);imagestring($img,5,30,rand(1,10),getRand(), $white);imagestring($img,5,45,rand(1,10),$num2, $green);imagestring($img,5,65,rand(1,10),"=", $blue);imagestring($img,5,80,rand(1,10),"?", $red);header("content-type:image/png");imagepng($img);imagedestroy($img);}function getRand(){$code = rand(0,1);switch ($code) {case 0:return "+";break;case 1:return "-";break;default:# code...break;}}?>

钟志远  江苏南京  钟志远