CAPTCHA Verification Code class instance _php techniques implemented in PHP

This article describes the PHP implementation of the CAPTCHA authentication code class, in the PHP program design has a very wide range of applications. Share to everyone for your reference. The specific methods are as follows:

The Authentication code class file is as follows:

<?php/** Captcha Authentication Code class * 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 Verification Code 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);
 Writes a random number to 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); Set background color $values = arrAy (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), 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 interference Polygon Bottom chart * * Text/for ($i = 0; $i < strlen ($authnum); $i + +) {$font = Imagecolorallocate ($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 ($im, Mt_rand (0,255), Mt_rand (0,255), Mt_rand (0, 255)); 
 Set the miscellaneous point color Imagesetpixel ($im, Mt_rand (0, $PW), Mt_rand (0, $ph), $dist); /* Add the Jamming line * * for ($i =0; $i < $lnum; $i + +) {$dist = Imagecolorallocate ($im, Mt_rand (50,255), Mt_rand (150,255), Mt_rand (200,255)); Set Line Color Imageline ($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}/** check Verification code * @param String $captcha Verification Code * @param int $flag validation successful 0: Do not clear session 1: Clear Session * @return Boolean
 */Public function check ($captcha, $flag =1) {if (empty ($captcha)) {return false; }else{if (strtoupper ($captcha) = = $this->captcha_session ($this->sname) {//Detect Verification code if ($flag ==1) {$this-&GT;CAPTC
  Ha_session ($this->sname, ");
  return true;
  }else{return false; }}/* Generate random number function * @param int $length need randomly generated string numbers * @return String */Private function random ($length) {$hash = '
 ';
 $chars = ' ABCDEFGHIJKLMNPQRSTUVWXYZ23456789 ';
 $max = strlen ($chars)-1;
 for ($i = 0; $i < $length; $i + +) {$hash. = $chars [Mt_rand (0, $max)];
 return $hash; /** Validation code 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?>

The Demo sample program is as follows:

<?php 
  session_start (); 
  Require_once (' Captcha.class.php '); 
 
  $obj = new Captcha ($sname);   # Create Captcha Class object 
                  # $sname to save the session name for CAPTCHA, leave it blank, and leave it blank for ' M_captcha ' 
 
  $obj->create ($length, $param);  #创建Captcha并输出图片 
                  # $length for Captcha length, can be left blank, defaults to 4 
                  /* $param = Array ( 
                      ' width ' =>    captcha character width 
                      ' Height ' =>    captcha character height 
                      ' pnum ' =>    number of interference points
                      ' Lnum ' => 2     interference lines 
                      can be left blank 
                  * * 
  $obj->check ($captcha, $flag); # Check that the user entered the validation code correctly, True or False 
                  # $captcha The authentication code entered for the user, required 
                  # $ Flag can be left blank, the default is 1  
                  #    1: Automatically clear captcha session # 0 after successful validation 
                  : Captcha session is    not cleared after successful verification, for Ajax checking 
?>

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