C++ friend function for Measure

#include <iostream>
using namespace std;
class Measure//from  ww w .j  a  v  a2  s .  co m
{
   private:
   int feet;
   float inches;
   public:
   Measure() : feet(0), inches(0.0)
   {  }
   Measure(int ft, float in) : feet(ft), inches(in)
   {  }
   void showdist()
   { cout << feet << "\'-" << inches << '\"'; }
   friend float square(Measure);    //friend function
};
float square(Measure d)          //return square of
{                              //this Measure
    float fltfeet = d.feet + d.inches/12;  //convert to float
    float feetsqrd = fltfeet * fltfeet;    //find the square
    return feetsqrd;               //return square feet
}
int main()
{
    Measure dist(3, 6.0);         //two-arg constructor (3'-6")
    float sqft;
    sqft = square(dist);           //return square of dist
    and square
    cout << "\nMeasure = "; dist.showdist();
    cout << "\nSquare = " << sqft << " square feet\n";
    return 0;
}