/trunk/book/manage/yzm.php

<?php

session_start();//??session

$randval;

for($i = 0; $i<4; $i++){

    //??A-Z???ASCII???

    $randstr = mt_rand(ord('A'), ord('Z'));//ord($str)?????ASCII

    $randv = mt_rand(0, 10);//??0?10

    global $randval;

    //??0-9??????

    if($randv % 2 == 0){//?????,????

        $randval .= mt_rand(0, 9);

    }else{//????????,?chr??

        $randval .= chr($randstr);//chr()?????? ascii ????????? 

    }

}

$_SESSION["randval"] = $randval;

$intheight = 18;//????????

$intwidth = 50;//????????,?????

$img = imagecreatetruecolor($intwidth, $intheight);

$fontcolor = imagecolorallocate($img, 255, 0, 0);

$backcolor = imagecolorallocate($img, 255, 255, 255);

imagefill($img, 0, 0, $backcolor);

//??

imageline($img, mt_rand(0,$intwidth/3), mt_rand(0,$intheight/3), mt_rand($intwidth/3,$intwidth), mt_rand($intheight/3,$intheight), $fontcolor);

imageline($img, mt_rand($intwidth/3, $intwidth), mt_rand(0, $intheight/3), mt_rand(0, $intwidth/3), mt_rand(0, $intheight/3), $fontcolor);

//??img???????

imagestring($img, 8, mt_rand(0, $intwidth - strlen($randval) * 10), mt_rand(0, $intheight-12), $randval, $fontcolor);

imagegif($img);

imagedestroy($img);

?>