---Класс captcha----



<?php

class Captcha{

protected static $code='';

protected static $doc='';

function Captcha(){

self::$doc=$_SERVER['DOCUMENT_ROOT'];

if(!is_dir(self::$doc.'/tmp/')){

 mkdir(self::$doc.'/tmp',0755);

}

self::$code=self::gen();

}







function gen($length = 4) { $chars = 'QWERTYUIOPASDFGHJKLZXCVBNM0123456789'; $count = mb_strlen($chars); for ($i = 0, $result = ''; $i < $length; $i++) { $index = rand(0, $count - 1); $result .= mb_substr($chars, $index, 1); } return $result; }



function input(){

if(isset($_COOKIE['cpt'])){

self::clear();



}

$tmp=sha1(time());

$fp=fopen(self::$doc.'/tmp/'.$tmp. '_captcha.cache','w');

fwrite($fp,self::$code);

fclose($fp);

setcookie('cpt',$tmp,time()+60*5,'/');

return '<img src="/cimg.php?sid='.$tmp.'"><br/>Проверочный код:<br/><input type="text" name="captcha" value="" placeholder=" Введите код с картинки..."><br/>';







}

public static function image(){

header('Content-Type: image/png');

$im=imagecreatetruecolor(400,30);

$white=imagecolorallocate($im,255,255,255);

$grey=imagecolorallocate($im,128,128,128);

$black=imagecolorallocate($im,0,0,0);

imagefilledrectangle($im,0,0,399,29,$white);

$text=file_get_contents($_SERVER['DOCUMENT_ROOT'].'/tmp/'.$_GET['sid'].'_captcha.cache');

$font='9923.ttf';

//$text='test';

imagettftext($im,20,0,11,21,$grey,$font,$text);

imagettftext($im,20,0,10,20,$black,$font,$text);

imagepng($im);

imagedestroy($im);}



function check(){

$tcode=file_get_contents(self::$doc.'/tmp/'.$_COOKIE['cpt'].'_captcha.cache');

$code=$_POST['captcha'];

return ($code==$tcode);

self::clear();





}

function bug(){

$tcode=file_get_contents(self::$doc.'/tmp/'.$_COOKIE['cpt'].'_captcha.cache');

$code=$_POST['captcha'];

echo $tcode.'  |  '.$code;



}

function clear(){

return unlink(self::$doc.'/tmp/'.$_COOKIE['cpt'].'_captcha.cache');

setcookie('cpt','',time()-1,'/');



}

}//class

?>







-----Файл cimg.php ----- 





<?php

include_once $_SERVER['DOCUMENT_ROOT'].'/captcha.php';

Captcha::image();

?>



--------Пример------

<?php

include 'captcha.php';

$cpt=new Captcha();

If(!$cpt->check()){

//Error

}Else{

//Good

}



?>

<Form method="post">

<?=$cpt->input();?>

<Input type="submit" value="ok"></form>