BleepingComputer.com: Windows programming - Errors that I cant seem to find?

I have been following a tutorial of creating a basic window with C++, I understand 90% and I am researching some of the more complicated parts, although, when I go to compile with MinGW it throws two errors.

The first is: Undefined reference to 'GetStockObject@4'
And the second is: Undefined reference to 'Ellipse@20'

Do you think these are both to do with the painting because Ellipse obviously is so maybe there is something wrong there?

Here is my source code:

#include <windows.h>

// Fuction prototypes
LRESULT CALLBACK WndProc(HWND hwnd, UINT message, WPARAM wparam, LPARAM lparam);
int WINAPI WinMain( HINSTANCE hInstance, HINSTANCE hPrevInstance, LPSTR szCmdLine, int iCmdShow );

// Create WinMain()
int WINAPI WinMain( HINSTANCE hInstance, HINSTANCE hPrevInstance, LPSTR szCmdLine, int iCmdShow )
{
	#pragma region part 1 - STARTUP STUFF
	
	WNDCLASS wc;
	wc.cbClsExtra = 0;
	wc.cbWndExtra = 0;
	wc.hbrBackground = (HBRUSH)GetStockObject( BLACK_BRUSH );
	wc.hCursor = LoadCursor( NULL, IDC_ARROW );
	wc.hIcon = LoadIcon( NULL, IDI_APPLICATION );
	wc.hInstance = hInstance;
	wc.lpfnWndProc = WndProc;
	wc.lpszClassName = TEXT("Philip");
	wc.lpszMenuName = 0;
	wc.style = CS_HREDRAW | CS_VREDRAW;
	
	RegisterClass( &wc );
	
	HWND hwnd = CreateWindow(TEXT("Philip"), TEXT("My window's title"), WS_OVERLAPPEDWINDOW, 100, 100, 300, 300, NULL, NULL, hInstance, NULL );
	
	ShowWindow(hwnd, iCmdShow);
	UpdateWindow(hwnd);
	
	#pragma endregion
	
	#pragma region part 2 - ENTER A LOOP TO CONTINUALLY KEEP CHECKING WITH WIN O/S FOR USER INTERACTION
	
	MSG msg;
	while(GetMessage(&msg, NULL, 0, 0))
	{
		TranslateMessage(&msg);
		DispatchMessage(&msg);
	}
	
	#pragma endregion
	
	return msg.wParam;
}

LRESULT CALLBACK WndProc(HWND hwnd, UINT message, WPARAM wparam, LPARAM lparam)
{
	switch(message)
	{
		case WM_CREATE:
			Beep(50, 10);
			return 0;
			break;
		
		case WM_PAINT:
			{
				HDC hdc;
				PAINTSTRUCT ps;
				hdc = BeginPaint(hwnd, &ps); // Error here?
				Ellipse(hdc, 10, 10, 10, 10);
				EndPaint(hwnd, &ps);
			}
			return 0;
			break;
		
		case WM_DESTROY:
			PostQuitMessage(0);
			return 0;
			break;
	}	
	return DefWindowProc(hwnd, message, wparam, lparam);
}

Thanks, Wolfy87.

Ok, I have found that if I take out the line where it draws the ellipse and where the background colour is set then it compiles but the window will not show.

You need to link with gdi32.lib in Visual C++ and libgdi32.a in MINGW. If you have MINGW installed and its added to PATH variable, you can give following command:

gcc hello.c -l gdi32  -o hello.exe

Also try changing the Ellipse code to something like Ellipse(hdc, 10, 10, 100, 100); to make it visible on the window. If you keep both upper-left and lower-right corrdinates at (10,10) then radius of ellipse(circle) would be zero.

Legend! it worked perfectly, I did'nt realise I ever had to link in things like that with MinGW, I thought that was just in VC++ etc anyway, now to learn how to put buttons on there etc =]

Thank you so much for that, Wolfy87.

yw

I have removed my post, no longer needed..

In C/C++ sin() function takes angle parameter in Radians.
As far as your calculator is concerned, you are using it in Degree mode.

180 degrees = PI radians

So you can make a simple function to convert degree values to radian like

double deg2rad(float degree){
	const float PI = 3.1415;
	return degree * (PI / 180.0);
}

Now you can find out value of sin(90 degree) as sin(deg2rad(90.0))

Cant try it right now, 11 o clock at night and im on my ipod but im sure it will work perfectly, you are the god of C++ in my eyes at the moment

I spent over three hours trying to get it to work lol.

Thank you so much for all of your help, Wolfy87.