title: How to initialize 3 dimension vector with the size in C++
body: <p>For example, if we initialize <code>vector&lt;vector&lt;vector&lt;double&gt;&gt;&gt; f</code>, the dimension in each direction is not specified. So, I am wondering, what command should we insert to make <code>f</code> have size of <code>[3][4][5]</code>. Do we use new or something else?</p>
  
  <p>Thanks for helping me out!</p>