PHP print and echo not working
<p>I am new to PHP and I was making this form and I wanted to print some data but it is not displaying. What is wrong with it? Here's the code:</p>

<pre><code>&lt;form name="input" action="check.php" method="get"&gt;
            Unit number: 
            &lt;input type="number" name="unit" /&gt;
            &lt;input type="submit" value="Submit" /&gt;
            &lt;/form&gt;

            &lt;table&gt;
            &lt;tr&gt;&lt;td class="check-table"&gt;
            &lt;?php
            if($_GET[unit] = null) $output="&lt;p&gt;Please Enter A Unit Number&lt;/p&gt;";
            echo $output;
            ?&gt;
            &lt;/td&gt;&lt;/tr&gt;&lt;/table&gt;
</code></pre>

<p>Please Help?</p>
