验证码问题

session_start();
//随机码的个数
$_rnd_code = 4;

//创建随机码
for($i=0;$i $_nmsg .= dechex(mt_rand(0,15));
}

//保存在session里
$_session['code']=$_nmsg;

//设置长和高
$_width=75;
$_height=25;

//创建一张图像
$_img = imagecreatetruecolor($_width,$_height);

//白色
$_white = imagecolorallocate($_img,255,255,255);

//填充
imagefill($_img,0,0,$_white);

//黑色边框
$_black = imagecolorallocate($_img,0,0,0);
imagerectangle($_img,0,0,$_width-1,$_height-1,$_black);

//随机六个线条
for($i=0;$i $_rnd_color = imagecolorallocate($_img,mt_rand(0,255),mt_rand(0,255),mt_rand(0,255));
imageline($_img,rand(0,$_width),rand(0,$_height),rand(0,$_width),rand(0,$_height),$_rnd_color);

}
//输出验证码

for($i=0;$iimagestring($_img,5,$i*$_width/$_rnd_code+mt_rand(1,10),mt_rand(1,$_height/2),$_session['code']['$i'],$_black);

}
做了个验证码   结果输出的4个字符全是一样的   你们看一下是怎么回事

回复讨论(解决方案)

imagestring($_img,5,$i*$_width/$_rnd_code+mt_rand(1,10),mt_rand(1,$_height/2),$_SESSION['code'][ '$i'],$_black);
应该这样
imagestring($_img,5,$i*$_width/$_rnd_code+mt_rand(1,10),mt_rand(1,$_height/2),$_SESSION['code'][ $i],$_black);

( ! ) Notice: Undefined variable: _nmsg in \demo.php on line 10
Call Stack
# Time Memory Function Location
1 0.0006 146856 {main}( ) ..\demo.php:0

( ! ) Warning: Illegal string offset '$i' in \demo.php on line 42
Call Stack
# Time Memory Function Location
1 0.0006 146856 {main}( ) ..\demo.php:0

( ! ) Warning: Illegal string offset '$i' in \demo.php on line 42
Call Stack
# Time Memory Function Location
1 0.0006 146856 {main}( ) ..\demo.php:0

( ! ) Warning: Illegal string offset '$i' in \demo.php on line 42
Call Stack
# Time Memory Function Location
1 0.0006 146856 {main}( ) ..\demo.php:0

( ! ) Warning: Illegal string offset '$i' in \demo.php on line 42
Call Stack
# Time Memory Function Location
1 0.0006 146856 {main}( ) ..\demo.php:0



改成这样就可以了

<?phpheader('content-type:image/jpeg');session_start();//随机码的个数$_rnd_code = 4;$_nmsg = '';//创建随机码for($i=0;$i<$_rnd_code;$i++){$_nmsg .= dechex(mt_rand(0,15));}//保存在session里$_SESSION['code']=$_nmsg;//设置长和高$_width=75;$_height=25;//创建一张图像$_img = imagecreatetruecolor($_width,$_height);//白色$_white = imagecolorallocate($_img,255,255,255);//填充imagefill($_img,0,0,$_white);//黑色边框$_black = imagecolorallocate($_img,0,0,0);imagerectangle($_img,0,0,$_width-1,$_height-1,$_black);//随机六个线条for($i=0;$i<6;$i++){$_rnd_color = imagecolorallocate($_img,mt_rand(0,255),mt_rand(0,255),mt_rand(0,255));imageline($_img,rand(0,$_width),rand(0,$_height),rand(0,$_width),rand(0,$_height),$_rnd_color);}//输出验证码for($i=0;$i<strlen($_SESSION['code']);$i++){imagestring($_img,5,$i*$_width/$_rnd_code+mt_rand(1,10),mt_rand(1,$_height/2),$_SESSION['code'][$i],$_black);}imagejpeg($_img);?>

谢谢了啦  发钱了