What does [&] mean before function? : <p>What do the follow row of code mean?</p>

<pre><code>auto allowed = [&amp;](int x, const std::vector&lt;int&gt;&amp;vect){

....

}
</code></pre>

<p>I mean, what does <code>[&amp;]</code> do? and is it function with the same name of the variable??</p>

<p>Because it used in this way: <code>unsigned short ok = get_allowed(0, vect);</code></p>
