Measurement conversions in PHP
<p>I'm trying to do a PHP converter that convert measurements with basic and simple code as possible (new to this). I hope this image will help you understand what I'm trying to do:</p>

<p>I have created a <strong>HTML file</strong> with a form that looks like this: </p>

<pre><code>&lt;form action="converter.php" method="post"&gt;
 &lt;input type="text" name="number"&gt;
 &lt;select name="choose"&gt;
        &lt;option&gt;Choose&lt;/option&gt;
        &lt;option value="meter" id="meter"&gt;Meter&lt;/option&gt;
        &lt;option value="cm" id="cm"&gt;Cm&lt;/option&gt;
        &lt;option value="foot" id="fot"&gt;Fot&lt;/option&gt;
        &lt;option value="inches" id="tum"&gt;Tum&lt;/option&gt;
&lt;input type="submit" value="Convert!"&gt;
&lt;/form&gt;
</code></pre>

<p>And a <strong>PHP file</strong> that look like this, and it's not much but:</p>

<pre><code>&lt;?php    
$number = $_POST['number'];
$choose = $_POST['choose'];

$x = $number;    
echo "$number $choose  &lt;br&gt;";    
?&gt;
</code></pre>

<p>Aaaand I'm stuck. I dont really know how to convert the values, both mathematically and in code. Doesn't matter if you give me the whole code or a hint of what to do next, just need a push in the right direction.</p>

<p>Thank you!</p>