Help with Windows Program

This is a discussion on Help with Windows Program within the Windows Programming forums, part of the Platform Specific Boards category; Okay, I read a tutorial about creating Windows Program, then copied and pasted this script. For some reason it doesn't ...

  1. #1
    Registered User
    Join Date
    Aug 2006
    Posts
    19

    Help with Windows Program

    Okay, I read a tutorial about creating Windows Program, then copied and pasted this script. For some reason it doesn't work??

    Code:
    /*	Trim fat from windows*/
    #define WIN32_LEAN_AND_MEAN	
    #pragma comment(linker, "/subsystem:windows")
    /*	Pre-processor directives*/
    #include "stdafx.h"
    #include <windows.h>
    /*	Windows Procedure Event Handler*/
    LRESULT CALLBACK WndProc(HWND hwnd, UINT message, WPARAM wParam, LPARAM lParam)
    {
    	PAINTSTRUCT paintStruct;
    	/*	Device Context*/
    	HDC hDC; 
    	/*	Text for display*/
    	char string[] = "Hello, World!"; 
    	/*	Switch message, condition that is met will execute*/
    	switch(message)
    	{
    		/*	Window is being created*/
    		case WM_CREATE: 
    			return 0;
    			break;
    		/*	Window is closing*/
    		case WM_CLOSE: 
    			PostQuitMessage(0);
    			return 0;
    			break;
    		/*	Window needs update*/
    		case WM_PAINT: 
    			hDC = BeginPaint(hwnd,&paintStruct);
    			/*	Set txt color to blue*/
    			SetTextColor(hDC, COLORREF(0x00FF0000));
    			/*	Display text in middle of window*/
    			TextOut(hDC,150,150,string,sizeof(string)-1);
    			EndPaint(hwnd, &paintStruct);
    			return 0;
    			break;
    		default:
    			break;
    	}
    	return (DefWindowProc(hwnd,message,wParam,lParam));
    }
    /*	Main function*/
    int APIENTRY WinMain(HINSTANCE hInstance,
                         HINSTANCE hPrevInstance,
                         LPSTR     lpCmdLine,
                         int       nCmdShow)
    {
    	WNDCLASSEX  windowClass;		//window class
    	HWND		hwnd;				//window handle
    	MSG			msg;				//message
    	bool		done;				//flag saying when app is complete
    	/*	Fill out the window class structure*/
    	windowClass.cbSize = sizeof(WNDCLASSEX);
    	windowClass.style = CS_HREDRAW | CS_VREDRAW;
    	windowClass.lpfnWndProc = WndProc;
    	windowClass.cbClsExtra = 0;
    	windowClass.cbWndExtra = 0;
    	windowClass.hInstance = hInstance;
    	windowClass.hIcon = LoadIcon(NULL, IDI_APPLICATION);
    	windowClass.hCursor = LoadCursor(NULL, IDC_ARROW);
    	windowClass.hbrBackground = (HBRUSH)GetStockObject(WHITE_BRUSH);
    	windowClass.lpszMenuName = NULL;
    	windowClass.lpszClassName = "MyClass";
    	windowClass.hIconSm = LoadIcon(NULL, IDI_WINLOGO);
    	/*	Register window class*/
    	if (!RegisterClassEx(&windowClass))
    	{
    		return 0;
    	}
    	/*	Class registerd, so now create window*/
    	hwnd = CreateWindowEx(NULL,		//extended style
    		"MyClass",			//class name
    		"A Real Win App",		//app name
    		WS_OVERLAPPEDWINDOW |		//window style
    		WS_VISIBLE |
    		WS_SYSMENU,
    		100,100,			//x/y coords
    		400,400,			//width,height
    		NULL,				//handle to parent
    		NULL,				//handle to menu
    		hInstance,			//application instance
    		NULL);				//no extra parameter's
    	/*	Check if window creation failed*/
    	if (!hwnd)
    		return 0;
    	done = false; //initialize loop condition variable
    	/*	main message loop*/
    	while(!done)
    	{
    		PeekMessage(&msg,hwnd,NULL,NULL,PM_REMOVE);
    		if (msg.message == WM_QUIT) //check for a quit message
    		{
    			done = true; //if found, quit app
    		}
    		else
    		{
    			/*	Translate and dispatch to event queue*/
    			TranslateMessage(&msg); 
    			DispatchMessage(&msg);
    		}
    	}
    	return msg.wParam;
    }
    The computer says it's that NULL in red (but then again computers are stupid..)

  2. #2
    erstwhile
    Join Date
    Jan 2002
    Posts
    2,227
    I suspect that it's not the NULL you think it is; try changing the first parameter to the CreateWindowEx function call from NULL to zero.

    >>For some reason it doesn't work??<<

    This does not help us to help you. State the compiler you are using and explicitly state any errors or warnings you are getting; fortunately you have at least highlighted the problematic part in your code, which is helpful.
    CProgramming FAQ
    Caution: this person may be a carrier of the misinformation virus.

  3. #3
    Registered User
    Join Date
    Aug 2006
    Posts
    19
    I'm using Dev C++, and it says:
    [Warning] passing NULL used for non-pointer converting of 'HWIND__'...

  4. #4
    erstwhile
    Join Date
    Jan 2002
    Posts
    2,227
    AS I said, try changing the first parameter to the CreateWindowEx function call from NULL to zero. Null is specifically for pointers and should not be used where a numeric type is expected; the first parameter to CreateWindowEx requires a DWORD which is a numeric type.
    CProgramming FAQ
    Caution: this person may be a carrier of the misinformation virus.

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