gistfile1.cpp

#include <stdio.h>
#include <math.h>
#include <stddef.h>

class Square
{
private:
  float _edge;

public:
  @property float edge
  {
    get
    {
      return _edge;
    }
    set
    {
      _edge = value;
    }
  }
  
  @property float area
  {
    get
    {
      return _edge * _edge;
    }
    set
    {
      _edge = sqrtf(value);
    }
  }
};

void print(float edge, float area)
{
  printf("edge = %f, area = %f\n", edge, area);
}

int main()
{
  Square s;
  s.area = 25;
  print(s.edge, s.area);
  s.edge = 3;
  print(s.edge, s.area);
  return 0;
}