public accesor function

Hello,

I've run the following:

Code:

#include <iostream>

using namespace std;

class Rectangle
{
	private:
	int x, y, w, h;
	
	public:
	Rectangle();
	int get_width() {return w;}
	int get_height() {return h;}
};

class Area
{
	private:
	int area;
	
	public:
	Area();
	int get_area();
};

Area::Area()
{
	area = 0;
}

int Area::get_area()
{
	area = myRectangle.get_width() * myRectangle.get_height();
	return area;
}

Rectangle::Rectangle()
{
	x = 0;
	y = 0;
	w = 10;
	h = 20;
}

int main()
{
	Rectangle myRectangle;
	Area myArea();
	
	
	cout << myArea.get_area() << endl;
	cout << myRectangle.get_width() << endl;

	return 0;
}

I get the following errors:

Code:

class5.cpp: In member function ‘int Area::get_area()’:
class5.cpp:33: error: ‘myRectangle’ was not declared in this scope
class5.cpp: In function ‘int main()’:
class5.cpp:51: error: request for member ‘get_area’ in ‘myArea’, which is of non-class type ‘Area ()()’

How do I access the get_width() and get_height() functions in get_area()? Since they are public in Rectangle, shouldn't I be able to access them in Area? If I comment out the two lines giving me issues, I can access myRectangle.get_width() from main. I don't understand why I can access get_width() in main but not in get_area().

Originally Posted by swappo

Since they are public in Rectangle, shouldn't I be able to access them in Area?

Yes, if you had a Rectangle to access them with. Unfortunately, you don't, since the Area class does not have any Rectangle related member variable and its get_area() member function does not have any parameters related to Rectangle.

The C++ Compiler looks only at local and global variables. MyRectangle is neither for get_area. It's declared in another function, main. You can't access variables declared in a calling function (except passing them as an argument).

I tried putting an argument in the get_area function.

Code:

#include <iostream>

using namespace std;

class Rectangle
{
	private:
	int x, y, w, h;
	
	public:
	Rectangle();
	int get_width() {return w;}
	int get_height() {return h;}
};

class Area
{
	private:
	int area;
	
	public:
	Area();
	int get_area(Rectangle *myRectangle);
};

Area::Area()
{
	area = 0;
}

int Area::get_area(Rectangle *myRectangle)
{
	area = myRectangle->get_width() * myRectangle->get_height();
	return area;
}

Rectangle::Rectangle()
{
	x = 0;
	y = 0;
	w = 10;
	h = 20;
}

int main()
{
	Rectangle myRectangle;
	Area myArea();
	
	
	cout << myArea->get_area(&myRectangle) << endl;
	cout << myRectangle.get_width() << endl;

	return 0;
}

I got the following error.

Code:

class5.cpp: In function ‘int main()’:
class5.cpp:51: error: request for member ‘get_area’ in ‘myArea’, which is of non-class type ‘Area ()()’

I am not sure whether to pass the class to get_area() or to pass get_width() and get_height().

Code:

Area myArea;

Otherwise myArea is a function declaration.