data structure to keep track of "consumptions"
<p>hey everyone,<br>
i am writing a small application for my c++ class mini-project.<br>
it's about managing clients, lines and services at a telecom company.<br>
i am supposed to use a <code>Consumption</code> class wich is supposed to represent a monthly consumption of a service/line.</p>

<pre><code>class Consumption  
{  
private:  
     Ligne* m_line;//the line related to this consumption  
     Service* m_service;//service used by this line  
     int m_month;
  int m_year;  
  int m_units;//units of m_service used in the m_month of m_year  
public:  
     //some getters and setters  
     double price();//returns m_units * the service's price/unit
};
</code></pre>

<p>a line can use a maximum of 2 services/month.<br>
consumptions will be used to make a bill for a certain line.<br>
my question is, what's the best way to keep track of the created Consumptions? i mean what data structure may be the best to use? should i make any changes to the class?<br>
note that i am not using files to store anything.<br>
any help is appreciated...</p>
