How PHP implements code for random numbers and letters verification codes

PHP Implementation of random numbers, letters of the Verification Code

Customizable to generate CAPTCHA text size, number, interference items, etc., you can also customize the font of text validation ...

Nonsense not much to say, directly on the code:

<?phpclass captcha{private $_fontfile= ";        Private $_size=36;        Private $_width=200;        Private $_height=100;        Private $_length=4;        Private $_image=null;        Private $_snow=0;        Private $_pixel=0;    Private $_line=0; Public function __construct ($config =array ()) {if (Is_array ($config) &&count ($config) >0) {if (ISS ET ($config [' fontfile ']) &&is_file ($config [' fontfile ']) &&is_readable ($config [' fontfile '])) {$            this->_fontfile= $config [' Fontfile '];            }else{return false; if (Isset ($config [' size ']) && $config [' size ']>0) {$this->_size= (int) $config [' Size ']            ; if (Isset ($config [' width ']) && $config [' width ']>0) {$this->_width= (int) $config [' Wid            Th ']; if (Isset ($config [' height ']) && $config [' height ']>0) {$this->_height= (int)$config [' height ']; if (Isset ($config [' length ']) && $config [' length ']>0) {$this->_length= (int) $config ['            Length ']; if (Isset ($config [' Snow ']) && $config [' Snow ']>0) {$this->_snow= (int) $config [' Snow ']            ; } if (Isset ($config [' Pixel ']) && $config [' Pixel ']>0) {$this->_pixel= (int) $config [' Pix            El ']; if (Isset ($config [' line ')] && $config [' line ']>0) {$this->_line= (int) $config [' line ']            ;            } $this->_image=imagecreatetruecolor ($this->_width, $this->_height);         return $this->_image;        } else{return false;        }} Public Function Getcaptcha () {$white =imagecolorallocate ($this->_image,255,255,255);        Imagefilledrectangle ($this->_image,0,0, $this->_width, $this->_height, $white); $str = $this->_generatestr ($this->_length);        if (false=== $str) {return false;        } $fontfile = $this->_fontfile;            for ($i =0; $i < $this->_length; $i + +) {$size = $this->_size;            $angle =mt_rand ( -30,30);            $x =ceil ($this->_width/$this->_length) * $i +mt_rand (5,10);            $y =ceil ($this->_height/1.5);            $color = $this->_getrandcolor ();            Intercept for Chinese characters//$text =mb_substr ($str, $i, 1, ' utf-8 ');            $text = $str {$i};        Imagettftext ($this->_image, $size, $angle, $x, $y, $color, $fontfile, $text);        } if ($this->_snow) {$this->_getsnow ();            }else{if ($this->_pixel) {$this->_getpixel ();            } if ($this->_line) {$this->_getline ();        }} header (' Content-type:image/png ');        Imagepng ($this->_image);        Imagedestroy ($this->_image);    Return Strtolower ($STR); } privatefunction _getsnow () {for ($i =1; $i <= $this->_snow; $i + +) {imagestring ($this->_image,mt_rand (1,5), MT        _rand (0, $this->_width), Mt_rand (0, $this->_height), ' * ', $this->_getrandcolor ()); }} Private Function _getpixel () {for ($i =1; $i <= $this->_pixel; $i + +) {Imagesetpixel ($this        _image,mt_rand (0, $this->_width), Mt_rand (0, $this->_height), $this->_getrandcolor ()); }} Private Function _getline () {for ($i =1; $i <= $this->_line; $i + +) {imageline ($this->_image , Mt_rand (0, $this->_width), Mt_rand (0, $this->_height), Mt_rand (0, $this->_width), Mt_rand (0, $this->_        Height), $this->_getrandcolor ());        }} Private Function _generatestr ($length =4) {if ($length <1 | | $length >30) {return false; } $chars =array (' A ', ' B ', ' C ', ' d ', ' e ', ' f ', ' g ', ' h ', ' K ', ' m ', ' n ', ' P ', ' x ', ' y ', ' z ', ' a ', ' B ', ' C ' , ' D ', ' E ', ' F ', ' G ', ' H ', ' K ', ' M ', ' N ', ' P ', ' X ', ' Y ', ' Z ', 1,2,3,4,5,6,7,8,9);        $str =join (' ', Array_rand (Array_flip ($chars), $length));    return $str; } Private Function _getrandcolor () {return imagecolorallocate ($this->_image,mt_rand (0,255), Mt_rand (0,255), Mt_    Rand (0,255)); }}?>

2, testcaptcha.php

<?phprequire_once ' classgd.class.php '; $config =array (' fontfile ' = ' Fonts/simfang.ttf ',   //Introducing font files//' snow ') =>50, ' Pixel ' =>100, ' line ' =>10    ), $captcha =new captcha ($config); $captcha->getcaptcha ();? >

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