Simple captcha to prevent your guestbook or feedback form

captcha.php code:-

<?php
//Developed by: Dinangkur Kundu <dkundu@gmail.com>
//Version: 0.0.2
//Last revision Date: 15th February, 2007
//Company: Quantumcloud <http://www.quauntumcloud.com>

session_start(); //start session
header (”Content-type: image/png”); //define content type

$text = rand(100,999);

$_SESSION[”v_code”] = $text;

$height = 25; //height of the image
$width = 35; //width of the image

//create image
$image = imagecreate($width, $height) or die(”Cannot Initialize new GD stream”);
//define background color of the image
$background_color = imagecolorallocate($image, 255, 255, 255);
//define text color in the image
$text_color = imagecolorallocate($image, 233, 14, 91);
//Draw a string horizontally
imagestring($image, 5, 5, 3, $text, $text_color);
//Output a PNG image to either the browser or a file
imagepng($image);
//Destroy the image
imagedestroy($image);
?>
test.php code:-

<?php
session_start();
//if form not submit skip
if ($submit == “Submit”) {
if ($_POST[”v_code”] != $_SESSION[”v_code”] OR $_SESSION[”vercode”]==”) {
echo ‘<strong>Incorrect verification code.</strong><br>’;
} else {
echo ‘<strong>Verification successful.</strong><br>’;
};
}
?>
<form method=”post” action=”test.php”>
<div>Name:</div>
<input type=”text” name=”txt_name” />
<div>Enter Code:</div>
<input type=”text” name=”v_code” />
<div><img src=”captcha.php” /></div>
<input type=”submit” name=”submit” value=”Submit” />
</form>

Put both file in same directory and run test.php in your browser.

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