C++ Constructor adds objects using member function

#include <iostream>
using namespace std;
class Measure/*from   w  w w.  ja va  2 s . c  o m*/
{
   private:
   int feet;
   float inches;
   public:
   Measure() : feet(0), inches(0.0)
   {  }
   Measure(int ft, float in)  : feet(ft), inches(in)
   {  }
   void getdist()               //get length from user
   {
      cout << "\nEnter feet: ";  cin >> feet;
      cout << "Enter inches: ";  cin >> inches;
   }
   void showdist()
   { cout << feet << "\'-" << inches << '\"'; }
   void add_dist(Measure,  Measure) const;    //declaration
};
//add lengths d2 and d3
void Measure::add_dist(Measure d2,  Measure d3) const
{
   inches = d2.inches + d3.inches; //add the inches
   feet = 0;                       //(for possible carry)
   if(inches >= 12.0)              //if total exceeds 12.0,
   {                            //then decrease inches
       inches -= 12.0;              //by 12.0 and
       feet++;                      //increase feet
    }                            //by 1
    feet += d2.feet + d3.feet;      //add the feet
}
int main()
{
    Measure dist1, dist3;          //define two lengths
    Measure dist2(11, 6.25);       //define and initialize dist2
    dist1.getdist();                //get dist1 from user
    dist3.add_dist(dist1, dist2);   //dist3 = dist1 + dist2
    cout << "\ndist1 = ";  dist1.showdist();
    cout << "\ndist2 = ";  dist2.showdist();
    cout << "\ndist3 = ";  dist3.showdist();
    cout << endl;
    return 0;
}