some class exercise

[abbassi]

Hi,

Please read the exercise no.2 of this: http://books.google.com/books?id=We2...epage&q&f=true

I've written below code for that. I know this code is not complete but this exercise is somewhat hard.

#include "Simple_window.h"  
#include "Graph.h"         
#include <iostream>

double curve(double x) {return x*x; }

//---------------------------------------

class FCT:public Shape {
public:
	FCT (Fct f, double _r1, double _r2, Point _xy, int _count = 100,
		 double _xscale = 25, double _yscale = 25): r1(_r1), r2(_r2),
		 xy(_xy), count(_count), xscale(_xscale), yscale(_yscale) 
	{
		if(r2-r1 <= 0) error("Bad graphing range");
		if(count <= 0) error("Non-positive graphing count");
		double dist = (r2-r1)/count;
		double r = r1;
		for(int i=0; i<count; i++) {
			add(Point(xy.x+int(r*xscale), xy.y-int(f(r)*_yscale)));
			r += dist;
		}
	}

		void reset_orig(Point _xy)   { xy = _xy;  }
		void reset_count(int c)      { count = c; } 
		void reset_r1(double _r1)    { r1 = _r1;  }
		void reset_r2(double _r2)    { r2 = _r2;  }
		void reset_xscale(double xs) { xscale = xs; }
		void reset_yscale(double ys) { yscale = ys; }

private:
	int count;
	double r1, r2, xscale, yscale;
	Point xy;
};

//-----------------------------------------------

int main()
	try
{
	Simple_window win(Point(100,100), 600, 400, "test");
	FCT g(curve, -10, 10, Point(200,200), 100, 25, 25);
	Text t(Point(200,200),"X");
	g.reset_orig(Point(300,300));


	win.attach(t);
	win.attach(g);
	g.reset_orig(Point(300,300));
	win.attach(g);
	win.wait_for_button();
	return 0;
}
catch(exception& e) {
	// some error reporting
	return 1;
}
catch(...) {
	// some more error reporting
	return 2;
}

//------------------------------------------------------------------------------

The definition of the Function is right here (15.3):

http://books.google.com/books?id=We2...epage&q&f=true

I defined a class named FCT (rather than Fct, I'll say its reason latter ). Now the class is defined and is just like the class Function.

I don't know could I understand the exercise correctly or not.
I DON'T WANT THE CODE. Just guide me how to solve it please.

[laserlight]

What exactly is the problem that you're facing?

[abbassi]

I reviewed and edited the question.
I hope it is fine now

[abbassi]

This time I wrote the following code for the exercise:

#include "Simple_window.h"  
#include "Graph.h"         
#include <iostream>

double curve(double x) {return x*x; }

//---------------------------------------

class FCT:public Shape {
public:
    FCT (Fct _f, double _r1, double _r2, Point _xy, int _count = 100,
        double _xscale = 25, double _yscale = 25): f(_f), r1(_r1), r2(_r2),
        xy(_xy), count(_count), xscale(_xscale), yscale(_yscale) 
    {
        if(r2-r1 <= 0) error("Bad graphing range");
        if(count <= 0) error("Non-positive graphing count");
        dist = (r2-r1)/count;
        r = r1;
        for(int i=0; i<count; i++) {
            add(Point(xy.x+int(r*xscale), xy.y-int(f(r)*yscale)));
            r += dist;
        }
    }

    void reset_fct(Fct _f)       { reset(_f); }
    void reset_orig(Point _xy)   { xy = _xy;    reset(); }
    void reset_count(int c)      { count = c;   reset(); } 
    void reset_r1(double _r1)    { r1 = _r1;    reset(); }
    void reset_r2(double _r2)    { r2 = _r2;    reset(); }
    void reset_xscale(double xs) { xscale = xs; reset(); }
    void reset_yscale(double ys) { yscale = ys; reset(); }
    void reset(Fct f = 0) {
        for(int i=0; i<count; i++) {
            set_point(i,(Point(xy.x+int(r*xscale), xy.y-int(f(r)*yscale))));
            r += dist;
        }
    }


private:
    Fct f;
    int count;
    double r, dist, r1, r2, xscale, yscale;
    Point xy;
};

//-----------------------------------------------

int main()
    try
{
    Simple_window win(Point(100,100), 600, 400, "test");
    FCT g(curve, -10, 10, Point(200,200), 100, 25, 25);
    g.reset_orig(Point(300,300));
    win.attach(g);
    win.wait_for_button();
    return 0;
}
catch(exception& e) {
    // some error reporting
    return 1;
}
catch(...) {
    // some more error reporting
    return 2;
}

//------------------------------------------------------------------------------

I get some errors:
1- Error 8 error C2436: 'f' : member function or nested class in constructor initializer list c:\users\cs\documents\visual studio 2012\projects\test_3\test_3\test_3.cpp 15

2- 9 IntelliSense: "f" is not a nonstatic data member or base class of class "FCT" c:\Users\CS\Documents\Visual Studio 2012\Projects\test_3\test_3\test_3.cpp 13

What is the type of the Fct, as the book says:

What is the type Fct that we used to represent a function argument? It is a variant of a standard library type called std::function that can "remember" a function to be called later. Fct requires its argument to be a double and its return type to be a double.

And the definition of class Shape is also here:
http://books.google.com/books?id=We2...epage&q&f=true

No help!?

[VictorN]

What is the type of the Fct, as the book says:

What is the type Fct that we used to represent a function argument? It is a variant of a standard library type called std::function that can "remember" a function to be called later. Fct requires its argument to be a double and its return type to be a double.

And the definition of class Shape is also here:
http://books.google.com/books?id=We2...epage&q&f=true

No help!?

And where in your code this Fct is declared/defined?

[abbassi]

The Fct here acts as in a type. For example if I write Fct h; it doesn't show any error even when running. Please have a look at the definition of Function in second link of my first post of here.

I don't know where really is the declaration/definition of Fct. May be in the library files (that I've included them in the program).
Anyway, the problem here, I think, is about copying/replacing the two Fcts which has occurred in the declaration of the FCT's constructor.