PHP利用GD函式實作一個簡單的驗證碼

$img=imagecreatetruecolor(100, 40);
$red=imagecolorallocate($img, 255, 0, 0);
$green=imagecolorallocate($img, 0, 255, 0);
$blue=imagecolorallocate($img, 0, 0, 255);
$white=imagecolorallocate($img, 255, 255, 255);
$black=imagecolorallocate($img, 0, 0, 0);
//生成图片
imagefill($img, 0, 0, $black);
//设置验证码
$code="";
for($i=0;$i<5;$i  ){
$code.=rand(0,9);
}
//验证码写到图片中
imagestring($img, 5, 20, 15, $code, $white);
//加点儿干扰
for($i=0;$i<10;$i  ){
imagesetpixel($img, rand(0,100), rand(0,40), $red);
imagesetpixel($img, rand(0,100), rand(0,40), $green);
imagesetpixel($img, rand(0,100), rand(0,40), $blue);
}
//再加点儿干扰
for($i=0;$i<1;$i  ){
imageline($img, rand(0,50), rand(0,20), rand(50,100), rand(20,40), $red);
imageline($img, rand(0,50), rand(0,20), rand(50,100), rand(20,40), $green);
imageline($img, rand(0,50), rand(0,20), rand(50,100), rand(20,40), $blue);
}
header("Content-type:image/png");
imagepng($img);
imagedestroy($img);
?>

驗證碼, PHP