session_start();

$image=imagecreatetruecolor(200, 60);

$bgcolor=imagecolorallocate($image, 255, 255, 255);

imagefill($image, 0, 0, $bgcolor);

$fontface='SIMHEI.TTF';

$strdb=array('幕','课','网','赞');

$captcha_code="";

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

$fontcolor=imagecolorallocate($image, rand(0,120), rand(0,120), rand(0,120));

$cn=$strdb[$i];

$captcha_code.=$cn;

imagettftext($image, mt_rand(20, 24), mt_rand(-60, 60), (40*$i+20), mt_rand(30, 35), $fontcolor, $fontface, $cn);

}

$_SESSION['authcode']=$captcha_code;