How to render a variable inside another?
<p>I want to place the variable $all right in the middle of $code, which is HTML code that I gathered from another file. My current code is like this.</p>

<pre><code>ob_start();
---code here---
$all = ob_get_clean();
$code = file_get_contents("file.txt");
echo $code;
</code></pre>

<p>file.txt would look a little something like this.</p>

<pre><code>&lt;html&gt;
&lt;head&gt;
&lt;title&gt;Title&lt;/title&gt;
&lt;/head&gt;
&lt;body&gt;
---HTML code here---
$all
---More HTML code---
&lt;/body&gt;
&lt;/html&gt;
</code></pre>

<p>What should I do so that when I echo $code, $all is rendered inside it?</p>
