e the <a href="adjacency_list.html#sec:iterator-constructor">edge iterator
constructor</a> of the graph. This is typically more efficient than using <tt>add_edge()</tt>.
Pointers to the <tt>edge_array</tt> can be viewed as iterators, so we can call
the iterator constructor by passing pointers to the beginning and end of the
array.
<pre>
    Graph g(edge_array, edge_array + sizeof(edge_array) / sizeof(Edge), num_vertices);
</pre>
<p>Instead of creating a graph with a certain number of vertices to begin with,