php isset() is_string() not working
<p>I have a rough php script that sees if a user has filled in the html form input after they have clicked submit. I am having a problem with getting isset() and is_string() to work. If I use isset() the form is emailed even if the form inputs are left blank, is_string() throws an error messages even if the form input are filled in. I have tried !isset() and that still sends blank input. The only thing working is if I use == NULL. At this moment in time I am not going to validate the input as I am trying to understand why this isn't working as I am pretty new to PHP.</p>

<pre><code>$subject = "Feedback from Your Website.";
$email = ($_POST['email']);
$name = ($_POST['name']);
$message = ($_POST['feedback']);

if (isset($_POST["name"]))
{
    //send message
    mail($subject, $name, $email, $message);
}

else
{
    //error message
    echo "Please do not miss out any fields";
}
</code></pre>

<p>I also tried:</p>

<pre><code>if (isset($_POST["name"], $_POST['email']))
{ }

if (isset($name, $email))
{ }

if (is_string($name || $email))
{ }
</code></pre>

<p>But all failed, so far all that's working is:</p>

<pre><code>if ($name == NULL || $email == NULL || $message == NULL)
{ }
</code></pre>

<p>Thank you in advance.</p>
