Approximate arithmetic operators

A new Duration can also be obtained by dividing a Duration by an integer, but the result of such division is rounded to the nearest second. The quotient of two Durations may also be taken, yielding a floating point value; this operation is useful for computing approximate ratios:

       Duration user,total;
       ...
       cout
           << "User time as a percentage of total time = "
           << (user/total)*100
           << endl;