1、请输入右边的验证码: <input name="auth_number" type="text" size="4" maxlength="4" class="input1"> <img src="auth_img.php" width="80" height="20" border=0 alt="">
2、auth_img.php <? session_start();
$img_width=80; $img_height=20;
srand(microtime() * 100000); for($ti=0;$ti<4;$ti++) { $new_number.=dechex(rand(0,15)); }
$_SESSION[check_auth_number]=$new_number; $number_img=imageCreate($img_width,$img_height); ImageColorAllocate($number_img,255,255,255); for($i=1;$i<=128;$i++) { imageString($number_img,1,mt_rand(1,$img_width),mt_rand(1,$img_height),"*",imageColorAllocate($number_img,mt_rand(200,255),mt_rand(200,255),mt_rand(200,255))); } for($i=0;$i<strlen($HTTP_SESSION_VARS[check_auth_number]);$i++) { imageString($number_img,mt_rand(3,5),$i*$img_width/4+mt_rand(1,8),mt_rand(1,$img_height/4), $HTTP_SESSION_VARS[check_auth_number][$i],imageColorAllocate($number_img,mt_rand(0,100),mt_rand(0,150),mt_rand(0,200))); } header("Content-type: image/png"); ImagePng($number_img); ImageDestroy($number_img); ?>
3、验证部份 function check_auth_number($auth_number) { if($auth_number!=$_SESSION[check_auth_number] || empty($_SESSION[check_auth_number])) { echo "<Script Language =\"JavaScript\">\n history.back();\n alert(\" 图片验证码错误 \");\n </Script> \n"; exit(); } }
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