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 X() { return x_; }
//    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