undeclared php variable in contact form - php

Question

I'm having problems with a simple contact form.
The error I'm getting is:
Notice: Undefined index: terms in contact.php on line 29
Attention! You have to check the Privacy Policy box to accept our terms.
Code:
if (!defined("PHP_EOL")) define("PHP_EOL", "\r\n");
$name = $_POST['name'];
$email = $_POST['email'];
$comments = $_POST['comments'];
$terms = $_POST['terms']; // <---- line 29
if(trim($terms) == '') {
echo '<div class="alert error"><div class="msg">Attention! You have to check
the Privacy Policy box to accept our terms.</div></div>';
exit();
}
if(trim($comments) == '') {
echo '<div class="alert error"><div class="msg">Attention! Please enter your
message.</div></div>';
exit();
}
if(get_magic_quotes_gpc()) {
$comments = stripslashes($comments);
}
The template file is below:
<form action="<?php echo $this->config->get('config_url').'ajax/contact.php' ?>" method="post" id="contact_form" enctype="multipart/form-data">
<table>
<tr>
<td>
<label for="name"><?php echo $entry_name; ?></label>
<input type="text" name="name" id="name" style="margin-right:20px" value="<?php echo $name; ?>" />
<?php if ($error_name) { ?>
<span class="error"><?php echo $error_name; ?></span>
<?php } ?>
</td>
<td>
<label for="email"><?php echo $entry_email; ?></label>
<input type="text" name="email" id="email" value="<?php echo $email; ?>" />
<?php if ($error_email) { ?>
<span class="error"><?php echo $error_email; ?></span>
<?php } ?>
</td>
</tr>
</table>
<label for="enquiry"><?php echo $entry_enquiry; ?></label>
<textarea name="enquiry" id="enquiry" cols="30" rows="5"><?php echo $enquiry; ?></textarea>
<?php if ($error_enquiry) { ?>
<span class="error"><?php echo $error_enquiry; ?></span>
<?php } ?>
<input type="checkbox" name="terms" value="<?php echo $terms; ?>" />
<label for="terms">Tick this box to confirm you comply with our Privacy Terms</label>
<input type="submit" id="submit" value="<?php echo $button_continue; ?>" class="button dark-bt" />
</form>

Answer 1

Try this:
$terms = isset($_POST['terms']) ? $_POST['terms'] : '';
You will get the checkbox field only if it is checked by the user in the form.
So, always check like this for checkbox and radio buttons.