Here we have three Files :
1) Image.php , which is used to create Captcha code image.
2) form.php, which is used to shown captcha code image and take input from user.
3) Result.php, is used to check whether the Code in image and the user entered both
are same or not.
Image.php
=========================
<?php
header("Content-type: image/png");
$string = "abcdefghijklmnopqrstuvwxyz0123456789";
for($i=0;$i<6;$i++){
$pos = rand(0,36);
$str .= $string{$pos};
}
$img_handle = ImageCreate (60, 20) or die ("Cannot Create image");
//Image size (x,y)
$back_color = ImageColorAllocate($img_handle, 255, 255, 255);
//Background color RBG
$txt_color = ImageColorAllocate($img_handle, 0, 0, 0);
//Text Color RBG
ImageString($img_handle, 31, 5, 0, $str, $txt_color);
Imagepng($img_handle);
session_start();
$_SESSION['img_number'] = $str;
?>
Form.php
==================
<form action="result.php" method="post">
<img alt="Random Number" src="image.php">
<input type="text" name="num"><br>
<input type="submit" name="submit" value="Check">
</form>
Result.php
=====================
<?php
session_start();
if($_SESSION['img_number'] != $_POST['num']){
echo'The number you entered doesn't match the image.<br>
<a href="form.php">Try Again</a><br>';
}else{
echo'The numbers Match!<br>
<a href="form.php">Try Again</a><br>;
}
?>