The perfect PHP code to generate CAPTCHA program

• Create a new PHP file captcha_code_file.php

The code is as follows

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Open Session First Session_Start (); Define foreground display verification code length & width $image _width = 120; $image _height = 40; $characters _on_image = 6; $font = './monofont.ttf '; The characters that can is 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"; To 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 colours 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, $code); /* Show CAPTCHA image in the page HTML page */ Header (' content-type:image/jpeg ');//Defining the image Type to is shown in browser widow Imagejpeg ($image);//showing the image Imagedestroy ($image);//destroying the image instance Set session, do validation $_session[' 6_letters_code ' = $code; function Hexrgb ($HEXSTR) { $int = Hexdec ($HEXSTR); Return Array ("Red" => 0xFF & ($int >> 0x10), "Green" => 0xFF & ($int >> 0x8), "Blue" => 0xFF & $int); }

Call page display authentication code page index.php

The code is as follows

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<?php Session_Start (); if (Isset ($_request[' Submit ')) {    //code for Check server Side Validation     if (Empty ($_session[' 6_letters_code ')) | |         strcasecmp ($_session[' 6_letters_code '), $_post[' 6_letters_code '] != 0     {          $msg = "The authentication code you entered is incorrect, please re-enter!";    }else{         echo "you entered the correct!";        //Captcha verification is correct. Final Code Execute here!    } }     ?> <style type= "Text/css" > . table{ Font-family:arial, Helvetica, Sans-serif; font-size:12px; Color: #333; Background-color: #E4E4E4; } . Table td{ Background-color: #F8F8F8; } </style> <form action= "" method= "Post" Name= "Form1" Id= "Form1" > <table width= "border=" 0 "align=" center "cellpadding=" 5 "cellspacing=" 1 "> <?php if (isset ($msg)) {?> <tr> &LT;TD colspan= "2" align= "center" valign= "Top" ><?php echo $msg;? ></td> </tr> <?php}?> <tr> &LT;TD align= ' right ' valign= ' top ' > Verification Code demo:</td> <td> "id= ' captchaimg ' onclick=" Refreshcaptcha (); "><br> <label for= ' message ' > Please enter the verification code:</label> <br> <input id= "6_letters_code" name= "6_letters_code" type= "text" > <br> If you do not see it, please <a href= ' Javascript:refreshcaptcha (); ' > Point I </a> Refresh! </p></td> </tr> <tr> <td>&nbsp;</td> <td><input name= "Submit" type= "Submit" onclick= "return Validate ();" value= "Submit" ></td> </tr> </table> </form> <script type= ' Text/javascript ' > The refresh request defined function Refreshcaptcha () { var img = document.images[' captchaimg ']; IMG.SRC = img.src.substring (0,img.src.lastindexof ("?")) + "? rand=" +math.random () *1000; } </script>