Compiler seems to reject class identifier initialization before member

Question

Please understand that I have a strong fever while writing this, and, in addition, it is years ago since I have used C++ - or classes for that matter.

My problem consists in the g++ compiler rejecting my calling of the class identifier (+ the member specifier), and the actual member of that class.

Here is what I mean:

class window{
public:
int borderX, borderY, menu_item;
};

If I choose to call one of these members (boderX, borderY, menu_item), like so:

window.borderX = [some value here];

I get an error in return:

error: expected unqualified-id before '.' token

When I look at cplusplus' website, this code is NOT grammatically incorrect. Yet, it refuses to compile?

Here is an example from cplusplus' website:

class CRectangle {
    int width, height;
  public:
    void set_values (int, int);
    int area (void) {return (width * height);}
};
CRectangle rect;
  rect.set_values (3,4);

This code does NOT compile either!

It returns this error:

error: 'rect' does not name a type

I don't understand why it returns these errors. Window IS used as an identifier - or a type thereof. And secondly, it won't EVEN compile the code from the very website itself which TEACHES the use of C++.

I am waiting to be corrected on these matters. Also, for the record, I am using MingW. Both Code::Blocks and Netbeans yield the same results (yes I KNOW they're IDEs, and not compilers.)

Answer 1

'window' defines the class, but you need to make an instance of that class in order to use it's non-static members and methods.

You can either create an instance on the stack,

window w;
w.borderX = [some value here];

Or create one on the heap,

window *w = new window();
w->borderX = [some value here];

Answer 2

Try this:

First you declare the class. In window.h

#include <iostream> // for cout and endl

class Window{
public:
    int borderX, borderY, menu_item;
};

In your main file where you start the program:

#include <window.h>
int main() {
    // 1. make an instance of Window
    Window w;         

    // 2. set some values
    w.borderX = 12;   
    w.borderY = 8;
    w.menu_item = 7;

    // 3. print the values
    std::cout << "X: "  << w.borderX 
              << " Y: " << w.borderY 
              << " menu item: " << w.menu_item << std::endl;

    //OR with a pointer
    // 1. create a new pointer that points to 
    //    an instance of Window (which is also create in the process)
    Window pw = new Window(); 

    // 3. set some values
    pw->borderX = 9;           
    pw->borderY = 12;
    pw->menu_item = 18;

    // 3. print the values
    std::cout << "X: "<< pw->borderX << " Y: " << pw->borderY 
              << " menu item: " << pw->menu_item << std::endl;

    // 4. Rule: for every *new* (new Window()) there is 1 delete
    //    So every pointer should be deleted somewhere 1 time to avoid memory leaks
    delete pw; 

    return 0;
}

And i hope you get better soon. Having fever is not funny.