Create Captcha Image Verification
June 19th, 2008 | posted by Anonymous
in
To avoid auto submitting application we can use captcha image verification. Using captcha method we make sure the form is filled by real human, not filed by a auto submitting robot.
1. Create captcha.php file. this file generate random number then display as image file. You can adjust width, height, bgcolor & forecoler of the image.
Demo
1. Create captcha.php file. this file generate random number then display as image file. You can adjust width, height, bgcolor & forecoler of the image.
<?php /* fornewbie.com * create captcha image verification * generate 5 digit random number */ session_start(); $RandomStr =rand(10000, 99999); //Generate 5 digit random number $imgWidth = 70; $imgHeight = 30; $bgColor = '#666666'; $frColor = '#FFFFFF'; $bgColorArr = sscanf($bgColor, '#%2x%2x%2x'); $frColorArr = sscanf($frColor, '#%2x%2x%2x'); $NewImage = imagecreatetruecolor($imgWidth, $imgHeight); $bgColor = imagecolorallocate($NewImage, $bgColorArr[0], $bgColorArr[1], $bgColorArr[2]); imagefill($NewImage, 0,0,$bgColor); $frColor = imagecolorallocate($NewImage, $frColorArr[0], $frColorArr[1], $frColorArr[2]); imagestring($NewImage, 5, 15, 5, $RandomStr, $frColor);// Draw a random string horizontally $_SESSION['key'] = $RandomStr;// carry the data through session header("Content-type: image/jpeg");// out out the image imagejpeg($NewImage);//Output image to browser ?>2. Create the Demo form (form.php)
<? if (isset($_POST['Submit'])) { session_start(); if ($_POST['code']==$_SESSION['key']) { $msg = "Verification Success"; } else { $msg = "Verification Failed"; } } ?> <html> <head> <title>Captcha Demo</title> <meta http-equiv="Content-Type" content="text/html; charset=iso-8859-1"> </head> <body> <form name="form1" method="post" action=""> <table width="300" border="0" cellspacing="0" cellpadding="0"> <tr> <td colspan="2">Captcha Demo </td> </tr> <tr> <td width="167"> </td> <td width="133"> <? if (!isset($_POST['Submit'])) { ?> <img src="captcha.php"> <? } else { ?> <? } ?> </td> </tr> <tr> <td>Type Security Code </td> <td><input name="code" type="text" id="code"></td> </tr> <tr> <td> </td> <td> <? if (isset($_POST['Submit'])) { ?> <?= $msg?> <? } ?> </td> </tr> <tr> <td> </td> <td><input type="submit" name="Submit" value="Submit"></td> </tr> </table> </form> </body> </html>3. Try the code.
Demo
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