• Hakki Dogusan <dogusanh tr.net> Mar 21 2004
• Jan Knepper <jan smartsoft.us> Mar 22 2004
• Hakki Dogusan <dogusanh tr.net> Mar 23 2004
• Scott Michel <scottm cs.ucla.edu> Mar 24 2004

Hi,

Code as follows:

#include <iostream>
using namespace std;

class Point
{
public:
     Point(): x_(0), y_(0) { }
     Point(double x, double y): x_(x), y_(y) {}
public:
     void X(double x) { x_ = x; }
     void Y(double y) { y_ = y; }
     double X() { return x_; }
     double Y() { return y_; }
private:
     double x_;
     double y_;
};

// ERROR
// with const gives "no match for function X()"
void print_point(const Point& p)
{
     cout << "x: " << p.X() << " y: " << p.Y();
}

int main()
{
     Point p1(10, 20);
     cout << "x: " << p1.X() << " y: " << p1.Y(); // OK
     print_point(p1); // ERROR
     return 0;
}


--
Regards,
Hakki Dogusan

Hakki Dogusan wrote:
 Hi,
 
 Code as follows:
 
 #include <iostream>
 using namespace std;
 
 class Point
 {
 public:
     Point(): x_(0), y_(0) { }
     Point(double x, double y): x_(x), y_(y) {}
 public:
     void X(double x) { x_ = x; }
     void Y(double y) { y_ = y; }


//    double Y() { return y_; }
     double X() const { return x_; }
     double Y() const { return y_; }
 private:
     double x_;
     double y_;
 };
 
 // ERROR
 // with const gives "no match for function X()"
 void print_point(const Point& p)
 {
     cout << "x: " << p.X() << " y: " << p.Y();
 }
 
 int main()
 {
     Point p1(10, 20);
     cout << "x: " << p1.X() << " y: " << p1.Y(); // OK
     print_point(p1); // ERROR
     return 0;
 }
 
 
 -- 
 Regards,
 Hakki Dogusan



-- 
ManiaC++
Jan Knepper

But as for me and my household, we shall use Mozilla... www.mozilla.org

Jan Knepper wrote:

 //    double X() { return x_; }
 //    double Y() { return y_; }


versus

     double X() const { return x_; }
     double Y() const { return y_; }



Thanks Jan,

I see dmc uses "thread warnings as error" way!.

Maybe error message could be a little detailed.


--
Regards,
Hakki Dogusan

Hakki Dogusan wrote:

 Jan Knepper wrote:
 
 //    double X() { return x_; }
 //    double Y() { return y_; }


 versus
 
     double X() const { return x_; }
     double Y() const { return y_; }


 
 Thanks Jan,
 
 I see dmc uses "thread warnings as error" way!.
 
 Maybe error message could be a little detailed.


Perhaps the compiler could be a little more detailed about its error
messages, but this kind of error is actually quite common.

Since you're passing a "const T" object/object ref into the method, the
compiler wants the method that takes a constant "this" object -- which is
why you need the const qualifier on the method declaration. See the C++
FAQ, Section 18, specifically 18.9.

-scooter