title: How to access elements of vector of pairs using a pointer?
body: <p>I am creating a vector of int pairs to create 28 domino pieces. After creating a piece, how do I access it using the pointer? I tried x->first, x[0]->first, x.first. I seem to be misunderstanding something.
  Here is the code, for example, how would I access the first element in the pair I just created.</p>
  
  <pre><code>vector &lt; pair &lt;int, int&gt;&gt;* x;
  
  x = new vector&lt;pair &lt;int, int&gt;&gt;;
  
  x-&gt;push_back(make_pair(1, 3));
  </code></pre>