please help me in numeric captcha

[sabin14]

How to add random numeric value captcha without images in a script. How to make it work
please provide code.

[atef]

<?php
function mathcaptcha()
{
$x=rand(1,9);
$y=rand(1,9);
$_SESSION['result'] = $x + $y;
$math = $x.' + '.$y.' = ';
$math .= "<input size="30" maxlength="20" type="text" name="captcha" />";
return $math; 
}

function checkcaptcha()
{
$result = false;
$check = isset($_SESSION['result']) ? $_SESSION['result'] : 'none'; 
unset($_SESSION['result']);

if(is_numeric($check) && is_numeric($_POST['captcha']) && ($check == $_POST['captcha'])) 
{
$result = true; 
} 
return $result; 
}
?>

[i0nutzxp]

Captcha without image is === NULL.
A bot can easily pass that.
If you really dont want with image you can put random questions but you wont be 99% sure about the 'protection'.

[manavworld]

especially robot access needed on web, so we can just block bot access via .htaccess, that could be better either :p