Summary of several methods for generating graphic verification codes in PHP

To generate the graphical verification code, you need to use the php GD library. 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;. Then restart the apache or iis environment.

Let’s first check whether our php has the gd library turned on.

The code is as follows

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代码如下	复制代码
if(extension_loaded('gd')) { echo '你可以使用gd '; foreach(gd_info() as $cate=>$value) echo "$cate: $value "; }else echo '你没有安装gd扩展'; ?>

if(extension_loaded('gd')) {

echo 'You can use gd
';

foreach(gd_info() as $cate=>$value)
echo "$cate: $value
";

}else

代码如下

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/**
* vCode(m,n,x,y) m个数字显示大小为n 边宽x 边高y
* 自己改写记录session $code
*/
session_start();
vCode(4, 15); //4个数字，显示大小为15

echo 'You do not have gd extension installed'; ?>

If there is return information, it is correct and can be used frequently Example 1

The code is as follows

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/**<🎜> * vCode(m,n,x,y) m numbers, display size is n, side width x, side height y<🎜> * Rewrite the record session $code<🎜> */<🎜> session_start(); <🎜> vCode(4, 15); //4 numbers, display size is 15<🎜> <🎜>function vCode($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 < $num; $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, $boer_color); <🎜> //Draw interference lines<🎜> for($i = 0;$i < 5;$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;$i < 50;$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 a 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 //First open the session
session_start();
//Define the length & width of the verification code displayed in the front desk
$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
$code = '';

$i = 0;
while ($i < $characters_on_image) {
$code .= substr($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; $i<$random_dots; $i++ ) {
imagefilledellipse($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; $i<$random_lines; $i++ ) {
imageline($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
//Set up session and do verification
$_SESSION['6_letters_code'] = $code;

function hexrgb ($hexstr)
{
$int = hexdec($hexstr);

return array("red" => 0xFF & ($int >> 0x10),
"green" => 0xFF & ($int >> 0x8),
"blue" => 0xFF & $int);
}

I personally recommend the second program code for generating verification codes. Students can try to compare it for reference. The last one is generated by W3C standards and also uses the php gd library.

Summary of several methods for generating graphic verification codes in PHP_PHP Tutorial