First, you can use the following program to get the verification code image. Note that the session variable is adjusted when the program generates the image.
getImage.php
include('kcaptcha.php');
session_start();
$captcha = new KCAPTCHA();
$_SESSION['captcha_keystring'] = $captcha->getKeyString();
?>
Next, call the verification code image through the following form, and verify whether the user input matches the verification code image value.
index.php
session_start();
$true_key_string = $_SESSION['captcha_keystring'];
echo $true_key_string;
?>
< html>
if(isset($_SESSION['captcha_keystring']) && $true_key_string == $_POST['keystring'])
{
echo "Correct";
}else
{
echo "Wrong";
}
?>