title: How to use vector default constructor?
body: <p>I recently learned how to use the vecor library in C++. I don't understant what is the vector default constructor or when should I use it. </p>
  
  <p>If for example I have a struct and want to create a vector of n structs. Is the following code valid:</p>
  
  <pre><code> struct item
  {
      string id;
      string name;
  };
  
      vector &lt;item&gt; vitem;
  
      vitem.push_back(item()); 
  </code></pre>
  
  <p>Does this vector have one element? or no elements at all?</p>