英文同数字 
Header("Content-type:image/png"); 
//定义header,声明图片文件,最好是png,无版权之扰;  
//生成新的四位整数验证码 
session_start();//开启session; 
$authnum_session = '';  
$str = 'abcdefghijkmnpqrstuvwxyz1234567890';  
//定义用来显示在图片上的数字和字母; 
$l = strlen($str); //得到字串的长度;  
//循环随机抽取四位前面定义的字母和数字;  
for($i=1;$i<=4;$i++) 
{  
$num=rand(0,$l-1);  
//每次随机抽取一位数字;从第一个字到该字串最大长度, 
//减1是因为截取字符是从0开始起算;这样34字符任意都有可能排在其中; 
$authnum_session.= $str[$num];  
//将通过数字得来的字符连起来一共是四位; 
} 
session_register("authnum_session"); 
//用session来做验证也不错;注册session,名称为authnum_session, 
//其它页面只要包含了该图片 
//即可以通过$_SESSION["authnum_session"]来调用 
//生成验证码图片, 
srand((double)microtime()*1000000); 
$im = imagecreate(50,20);//图片宽与高;  
//主要用到黑白灰三种色; 
$black = ImageColorAllocate($im, 0,0,0); 
$white = ImageColorAllocate($im, 255,255,255); 
$gray = ImageColorAllocate($im, 200,200,200);  
//将四位整数验证码绘入图片 
imagefill($im,68,30,$gray); 
//如不用干扰线,注释就行了; 
$li = ImageColorAllocate($im, 220,220,220); 
for($i=0;$i<3;$i++)  
{//加入3条干扰线;也可以不要;视情况而定,因为可能影响用户输入;  
imageline($im,rand(0,30),rand(0,21),rand(20,40),rand(0,21),$li); 
}  
//字符在图片的位置; 
imagestring($im, 5, 8, 2, $authnum_session, $white); 
for($i=0;$i<90;$i++) 
{//加入干扰象素 
imagesetpixel($im, rand()%70 , rand()%30 , $gray); 
} 
ImagePNG($im); 
ImageDestroy($im); 
?>  
中文 
/*     
* 文件:code.php     
* 作用:验证码生成     
*/     
session_start(); 
// 设置 content-type     
header("Content-type: image/png");     
// 创建图片     
$im = imagecreatetruecolor(120, 30);      
$ChineseChar = array("人","出","来","友","学","孝","仁","义","礼","廉","忠","国","中","易","白","者","火 ","土","金","木","雷","风","龙","虎","天","地",   
"生","晕","菜","鸟","田","三","百","钱","福 ","爱","情","兽","虫","鱼","九","网","新","度","哎","唉","啊","哦","仪","老","少","日",   
"月 ","星");     
// 创建颜色     
$fontcolor = imagecolorallocate($im, 255, 255, 255);     
$bg = imagecolorallocate($im, 0, 0, 0);     
// 设置文字     
for($i=0;$i<4;$i++) $text .= $ChineseChar[(array_rand($ChineseChar))];     
$_SESSION['code'] = $text; 
// 设置字体  [url]http://www.font.com.cn/downlist/s_12_3.html[/url] 有_GBK系列的字体下载,一般GD库都支持的! 
$font = 'gbk.ttf'; 
// 添加文字     
imagettftext($im, 18, 0, 11, 21, $fontcolor, $font, iconv("GB2312","UTF-8",$text));     
// 输出图片     
imagepng($im);     
imagedestroy($im);     
?> 
http://www.bkjia.com/PHPjc/319031.htmlwww.bkjia.comtruehttp://www.bkjia.com/PHPjc/319031.htmlTechArticle英文同数字 ?php Header("Content-type:image/png"); //定义header,声明图片文件,最好是png,无版权之扰; //生成新的四位整数验证码 session_start();//开启...