If no arguments are provided in the function, how do I test to see if it is left blank?
<pre><code>&lt;?php    
/* Copyright Date
--------------------------*/
function copyright_date($creation_year) {
    $current_year = date('Y');

    if ($creation_year == $current_year || $creation_year == '') {
     echo $current_year;
    } 
    else {
     echo $creation_year . '-' . $current_year;
    }   
}
?&gt;
</code></pre>

<p>If someone forgets to add the argument (the year the website was created), e.g.</p>

<pre><code>&lt;?php copyright_date(); ?&gt;
</code></pre>

<p>instead of:</p>

<pre><code>&lt;?php copyright_date(2009); ?&gt;
</code></pre>

<p><strong>how would I test to see if the argument was left blank?</strong> In my if statement, that's what $creation_year == '' is for, but since the argument isn't a string, it doesn't work.</p>
