PHP CAPTCHA Authentication Code class

<?php/** Captcha Certificate * date:2011-02-19 * Author:fdipzone/class captcha{//class start  
      
    Private $sname = '; Public function __construct ($sname = ") {//$sname CAPTCHA session name $this->sname = $sname = = '?  
    ' M_captcha ': $sname; 
    /** generate a CAPTCHA picture * @param int $length authentication length * @param Array $param parameters * @return IMG  
        * * Public Function Create ($length =4, $param =array ()) {Header ("content-type:image/png");   $authnum = $this->random ($length);  
          
        Generates a CAPTCHA character. $width = Isset ($param [' width '])?     $param [' width ']: 13; Text width $height = isset ($param [' height '])?   $param [' Height ']: 18; Text Height $pnum = isset ($param [' pnum '])?      $param [' Pnum ']: 100; Number of jamming pixels $lnum = isset ($param [' lnum '])?        $param [' Lnum ']: 2;                Number of interference lines $this->captcha_session ($this->sname, $authnum); WillRandom numbers are written into the session $PW = $width * $length +10;  
                      
        $PH = $height +6;                     $im = Imagecreate ($PW, $ph);  
        Imagecreate () Creates a new image with a blank image size of x_size and y_size.  $black = Imagecolorallocate ($im, 238,238,238); Sets the background color $values = Array (mt_rand (0, $PW), Mt_rand (0, $ph), Mt_ran D (0, $PW), Mt_rand (0, $ph), Mt_rand (0, $PW), Mt_rand (0, $ph), Mt_rand (0, $PW), Mt_rand (0  
        , $ph), Mt_rand (0, $PW), Mt_rand (0, $ph), Mt_rand (0, $PW), Mt_rand (0, $ph)); Imagefilledpolygon ($im, $values, 6, Imagecolorallocate ($im, Mt_rand (170,255), Mt_rand (200,255), Mt_rand (210,255)))   ; Set to disturb the polygon/* text/for ($i = 0; $i < strlen ($authnum); $i + +) {$font = Imag Ecolorallocate ($im, Mt_rand (0,50), Mt_rand (0,150), Mt_rand (0,200));/Set text color $x = $i/$length * $PW + rand (1, 6);                   Set the random x-coordinate $y = rand (1, $PH/3);   
        Set random y-coordinate imagestring ($im, Mt_rand (4,6), $x, $y, substr ($authnum, $i, 1), $font); }/* Add the jamming pixel */for ($i =0 $i < $pnum $i + +) {$dist = Imagecolorallocate ($im, Mt_ran D (0,255), Mt_rand (0,255), Mt_rand (0,255));   
        Set the miscellaneous point color Imagesetpixel ($im, Mt_rand (0, $PW), Mt_rand (0, $ph), $dist); }/* Add the =0/for ($i; $i < $lnum; $i + +) {$dist = Imagecolorallocate ($im, Mt_ran D (50,255), Mt_rand (150,255), Mt_rand (200,255));  
        Set Line Color Imageline ($im, Mt_rand (0, $PW), Mt_rand (0, $ph), Mt_rand (0, $PW), Mt_rand (0, $ph), $dist);      } imagepng ($im);  Output the image to the browser or file Imagedestroy ($im) in PNG format; Destroy an image}/** inspection certificate * @param String $captcha Verify * See more highlights in this column: HTTP://WWW.BIANCENG.CNHT tp://www.bianceng.cn/webkf/php/* @param int $flag VerificationAfter success 0: do not clear session 1: Clear Session * @return Boolean/Public function check ($captcha, $flag =1) {if (EM)  
        Pty ($captcha)) {return false; }else{if (strtoupper ($captcha) = = $this->captcha_session ($this->sname)) {//Verify the test code if (  
                $flag ==1) {$this->captcha_session ($this->sname, ");  
            return true;  
            }else{return false; * * Generate random number function * @param int $length need to randomly generate string numbers * @return Str  
        ing */Private function random ($length) {$hash = ';  
        $chars = ' ABCDEFGHIJKLMNPQRSTUVWXYZ23456789 ';  
        $max = strlen ($chars)-1;  
        for ($i = 0; $i < $length; $i + +) {$hash. = $chars [Mt_rand (0, $max)];  
    return $hash; /** Verification Session Processing method * @param String $name CAPTCHA Session name * @param string $value * @return string/Private function Captcha_session ($name  
            , $value =null) {if (Isset ($value)) {if ($value!== ') {$_session[$name] = $value;  
            }else{unset ($_session[$name]);  
        }else{return Isset ($_session[$name])? $_session[$name]: '; }}//class end?>

Demo

?  
    Session_Start ();  
      
    Require_once (' Captcha.class.php ');     $obj = new Captcha ($sname); # Create Captcha # $sname to save Captcha's session name, leave it blank and leave it blank for ' M_captcha ' $obj-&    Gt;create ($length, $param);  
                                    # Create CAPTCHA and output a picture # $length for Captcha, you can leave it blank and think 4 
                                            /* $param = Array (' width ' => captcha character width         ' Height ' => captcha character height ' pnum ' => 100 
                                            To disturb the number of ' Lnum ' => 2. ) can be left blank/* $obj ; Check ($captcha, $flag);  
    # Check to see if the user input test is correct, true or False # $captcha for the user input certificate, required                                # $flag can be left blank for 1 # 1: Automatically clear Captcha Sessio after successful verification N # 0: When the experience is successful, do not clear captcha session, used for Ajax check?>

Author: csdn blog proud Snow star Maple