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

in program have created constructor called point 2 values. have set, get, scale , translate function. i'm trying create function allows me distance between object , point. i'm have trouble though 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;     = 1;     cout << "\n default constructor called" << endl; }  inline point::point(double anx, double ay) {     cout << "\n regular constructor called"; }  inline point::~point() {     cout << "\n destructor called" << endl; }  inline void point::setpoint(double anx, double ay) {     thex = anx;     = 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 translated : " << offsetx << endl;     cout << "y translated : " << 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 value x : " << mypoint.getx() << endl;     cout << "\n value y : " << mypoint.gety() << endl;      cout << "\n x scaled 2 : " << mypoint.scalex(2) << endl;     cout << "\n y scaled 2 : " << mypoint.scaley(2) << endl;      mypoint.translate(2, 3);      cout << "\n main has finished" << endl;      return 0; } 

you need make point::getx() , point::gety() functions const so:

inline double point::getx() const {     return thex; } 

if not const cannot call them when parameter const reference.

then distance (changed return void 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 exponent 2. need include <cmath> std::sqrt.