Library management system source code php generates random verification code image code

Copy the code The code is as follows:

/**Default homepage **/
class DefaultController extends AppController
{
public function index() {
$len = 5;
$str = "ABCDEFGHIJKLNMPQRSTUVWXYZ123456789";
$im = imagecreatetruecolor (70, 20);
$bgc = imagecolorallocate($im, 255, 255, 255);
$bgtxt = imagecolorallocate($im, 220, 220, 220);
// Random palette
$colors = array(
imagecolorallocate($im, 255, 0, 0),
imagecolorallocate($im, 0, 200, 0),
imagecolorallocate($im, 0, 0, 255),
imagecolorallocate($im, 0, 0, 0),
imagecolorallocate($im, 255, 128, 0),
imagecolorallocate($im, 255, 208, 0),
imagecolorallocate($im, 98, 186, 245) ,
);
//Fill the background color
imagefill($im, 0, 0, $bgc);
//Get random numbers
$verify = "";
while (strlen($verify) < $len) {
$i = strlen($verify);
$random = $str[rand(0, strlen($str))];
$verify .= $random;
//Draw background text
imagestring($im, 6, ($i*10)+3, rand(0,6), $random, $bgtxt);
//Draw the main text information
imagestring($im, 6, ($i*10)+3, rand (0,6), $random, $colors[rand(0, count($colors)-1)]);
}
//Add random noise
for($i=0; $i<100; $ i++) {
$color = imagecolorallocate($im, rand(50,220), rand(50,220), rand(50,220));
imagesetpixel($im, rand(0,70), rand(0,20), $color );
}
//Save the verification code in $_SESSION
sess("verify", $verify);
//Output the image and release the cache
header('Content-type: image/png');
imagepng ($im);
imagedestroy($im);
}
};
?>

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