C++ Creating a function to get distance between two points - c++

Question

In my program I have created a constructor called Point with two values. I also have a set, get, scale and translate function. I'm trying to create a function that allows me to get the distance between the object and another point. I'm have trouble with it though any help would be brilliant.
#ifndef POINTMODEL
#define POINTMODEL
#define POINTDEB UG
#include <iostream>
#include <string.h>
using namespace std;
class Point {
public:
Point(void);
Point(double anX, double aY);
~Point();
void setPoint(double anX, double aY);
double getX();
double getY();
double scaleX(double theX);
double scaleY(double theY);
void translate(double theX, double theY);
void distance(const Point& aPoint);
protected:
private:
double theX;
double theY;
};
inline Point::Point(void)
{
theX = 1;
theY = 1;
cout << "\n The default constructor was called" << endl;
}
inline Point::Point(double anX, double aY)
{
cout << "\n regular constructor called";
}
inline Point::~Point()
{
cout << "\n the destructor was called" << endl;
}
inline void Point::setPoint(double anX, double aY)
{
theX = anX;
theY = aY;
}
inline double Point::getX()
{
return theX;
}
inline double Point::getY()
{
return theY;
}
inline double Point::scaleX(double theX)
{
return theX;
}
inline double Point::scaleY(double theY)
{
return theY;
}
inline void Point::translate(double offSetX, double offSetY)
{
cout << "X is translated by : " << offSetX << endl;
cout << "Y is translated by : " << offSetY << endl;
}
inline void Point::distance(const Point& aPoint)
{
}
#endif
Cpp file:
#include "Point.h"
using namespace std;
int main(void)
{
cout << "\n main has started" << endl;
//Point myPoint;
Point myPoint(1, 1);
myPoint.setPoint(1, 1);
cout << "\n The value for X is : " << myPoint.getX() << endl;
cout << "\n The value for Y is : " << myPoint.getY() << endl;
cout << "\n X scaled by 2 is : " << myPoint.scaleX(2) << endl;
cout << "\n Y scaled by 2 is : " << myPoint.scaleY(2) << endl;
myPoint.translate(2, 3);
cout << "\n main has finished" << endl;
return 0;
}

Answer 1

You need to make your Point::getX() and Point::getY() functions const like so:
inline double Point::getX() const
{
return theX;
}
If they are not const you cannot call them when the parameter is a const reference.
Then the distance is (changed return from void to double):
double distance(const Point & aPoint) const
{
const double x_diff = getX() - aPoint.getX();
const double y_diff = getY() - aPoint.getY();
return std::sqrt(x_diff * x_diff + y_diff * y_diff);
}
I have deliberately not used std::pow since the exponent is 2.
You also need to include <cmath> for std::sqrt.