Several ways to generate graphic verification codes in PHP_PHP tutorial

You need to use the php GD library to generate the graphical verification code. If you do not have an account with the GD library, we need to find extension=php_gd2.dll in the php.ini file and remove the previous ";" and then restart the apache or iis environment. ​ if(extension_loaded('gd')) {
echo 'You can use gd
';
foreach(gd_info() as $cate=>$value)
echo "$cate: $ value
";
}else
echo 'You do not have gd extension installed';
?>
If there is return information, it is correct and can be used frequently
Example 1
/**
* vCode(m,n,x,y) m numbers, display size is n, side width x, side height y
* Rewrite the record session by yourself $code
* www.jbxue.com
*/
session_start();
vCode(4, 15); //4 numbers, display size is 15
function vCode($num = 4, $size = 20 , $width = 0, $height = 0) {
!$width && $width = $num * $size * 4 / 5 + 5;
!$height && $height = $size + 10;
// Removed 0 1 O l etc.
$str = "23456789abcdefghijkmnpqrstuvwxyzABCDEFGHIJKLMNPQRSTUVW";
$code = '';
for ($i = 0; $i $code .= $str[mt_rand(0, strlen($str)-1)];
}
// Draw image
$im = imagecreatetruecolor($width, $height) ;
// Define the color to be used
$back_color = imagecolorallocate($im, 235, 236, 237);
$boer_color = imagecolorallocate($im, 118, 151, 199);
$text_color = imagecolorallocate($im, mt_rand(0, 200), mt_rand(0, 120), mt_rand(0, 120));
// Draw background
imagefilledrectangle($im, 0, 0, $width, $height, $back_color);
// Draw border
imagerectangle($im, 0, 0, $width-1, $height-1, $boer_color);
// Draw interference Line
for($i = 0;$i $font_color = imagecolorallocate($im, mt_rand(0, 255), mt_rand(0, 255), mt_rand(0, 255));
imagearc($im, mt_rand(- $width, $width), mt_rand(- $height, $height), mt_rand(30, $width * 2), mt_rand(20, $height * 2 ), mt_rand(0, 360), mt_rand(0, 360), $font_color);
}
// Draw interference points
for($i = 0;$i $font_color = imagecolorallocate($im, mt_rand(0, 255), mt_rand(0, 255), mt_rand(0, 255));
imagesetpixel($im, mt_rand(0, $width) , mt_rand(0, $height), $font_color);
}
// Draw verification code
@imagefttext($im, $size , 0, 5, $size + 3, $text_color, ' c:WINDOWSFontssimsun.ttc', $code);
$_SESSION["VerifyCode"]=$code;
header("Cache-Control: max-age=1, s-maxage=1, no-cache , must-revalidate");
header("Content-type: image/png;charset=gb2312");
imagepng($im);
imagedestroy($im);
}
?>
Example 2
An example of generating verification code developed using PHP, combined with session and GD library extensions (recommended by w3c), which can be easily used in projects. And the style is beautiful
session_start();
//Define the length & width of the front-end display verification code
$image_width = 120;
$image_height = 40;
$characters_on_image = 6;
$font = './ monofont.ttf';
//The characters that can be used in the CAPTCHA code.
//avoid confusing characters (l 1 and i for example)
$possible_letters = '23456789bcdfghjkmnpqrstvwxyz';
$random_dots = 10;
$random_lines = 30;
$captcha_text_color="0x142864";
$captcha_noice_color = "0x142864";
//Define the string to generate the verification code
/ /www.jbxue.com
$code = '';
$i = 0;
while ($i $code .= substr($possible_letters, mt_rand( 0, strlen($possible_letters)-1), 1);
$i++;
}
$font_size = $image_height * 0.75;
$image = @imagecreate($image_width, $image_height) ;
/* setting the background, text and noise colors here */
$background_color = imagecolorallocate($image, 255, 255, 255);
$arr_text_color = hexrgb($captcha_text_color);
$text_color = imagecolorallocate($image, $arr_text_color['red'],
           $arr_text_color['green'], $arr_text_color['blue']);
$arr_noice_color = hexrgb($captcha_noice_color);
$image_noise_color = imagecolorallocate($image, $arr_noice_color['red'],
               $arr_noice_color['green'], $arr_noice_color['blue']);
/* generating the dots randomly in background */
for( $i=0; $iimagefilledellipse($image, mt_rand(0,$image_width),
mt_rand(0,$image_height), 2, 3 , $image_noise_color);
}
/* generating lines randomly in background of image */
for( $i=0; $iimageline($image, mt_rand(0,$image_width), mt_rand(0,$image_height),
 mt_rand(0,$image_width), mt_rand(0,$image_height), $image_noise_color);
}
/* create a text box and add 6 letters code in it */
$textbox = imagettfbbox($font_size, 0, $font, $code);
$x = ($image_width - $textbox[4])/2;
$y = ($image_height - $textbox[5])/2;
imagettftext($image, $font_size, 0, $x, $y, $text_color, $font , $code);
/* Show captcha image in the page html page */
header('Content-Type: image/jpeg');// defining the image type to be shown in browser widow
imagejpeg($image);//showing the image
imagedestroy($image);//destroying the image instance
//设置session，做验证
$_SESSION['6_letters_code'] = $code;
function hexrgb ($hexstr)
{
  $int = hexdec($hexstr);
  return array("red" => 0xFF & ($int >> 0x10),
               "green" => 0xFF & ($int >> 0x8),
               "blue" => 0xFF & $int);
}
推荐第二个生成验证码程序代码，最后一个是W3C标准生成的也是利用了php gd库。

http://www.bkjia.com/PHPjc/440098.htmlwww.bkjia.comtruehttp://www.bkjia.com/PHPjc/440098.htmlTechArticle生成图形验证码需要使用php GD库来生成，如果你没开户GD库我们需要在php.ini文件找到extension=php_gd2.dll 去掉前面的;就行了,然后重启apache 或...