This tutorial will show you how to create a form with Captcha, Requirement(s): PHP Server, GD Graphics Library
1.Sessions in PHP are started by using the session_start() function. Like the setcookie( ) function, the session_start( ) function must come before any HTML, including blank lines, on the page.
<?php session_start(); ?>
2.Imagecreate - Create a new palette based image.
$img = imagecreate(40, 20);
3.The function imagecolorallocate creates a color using RGB (red,green,blue) format.
$black = imagecolorallocate($img, 0, 0, 0);
4.Displaying the random text on the captcha image
$numero = rand(100, 999);
5.Check if the security code and the session value are not blank and if the input text matches the stored text.
if(($_POST['check']) == $_SESSION['check']){
echo 'Input OK';
}else{
echo 'Input Wrong';
}
Files
index.php
<form method="POST" action="cc.php">
<img src="captchas.php"> <br />
<input type="text" size="10" name="check"> <br />
<input type="submit" name="submit" value="submit">
</form>
captchas.php
<?php
session_start();
//imagecreate -- Create a new palette based image
$img = imagecreate(40, 20);
//displaying the random text on the captcha image
$black = imagecolorallocate($img, 0, 0, 0);
$numero = rand(100, 999);
$number = $black . $numero;
$_SESSION['check'] = ($numero);
$white = imagecolorallocate($img, 255, 255, 255);
imagestring($img, 10, 8, 3, $numero, $white);
header ("Content-type: image/png");
imagepng($img);
?>
cc.php
<?php session_start();
//Sessions in PHP are started by using the
//session_start() function.
//Like the setcookie( ) function,
//the session_start function must come before any HTML,
//including blank lines, on the page.session_start();
//Check if the security code and
//the session value are not blank
//and if the input text matches the stored text
if(($_POST['check']) == $_SESSION['check']) {
echo 'Input OK';
}else{
echo 'Input Wrong';
unset($_SESSION['check']);
session_destroy();
}
?>