#include <windows.h>
#define EDIT1 11
WNDPROC g_oldproc;
BOOL CALLBACK MainProc(HWND hwnd, UINT msg, WPARAM wParam, LPARAM lParam);
LRESULT CALLBACK NewProc (HWND hwnd, UINT msg, WPARAM wParam, LPARAM lParam);
const char g_szClassName[] = "subclassing example";

LRESULT CALLBACK WndProc(HWND hwnd, UINT msg, WPARAM wParam, LPARAM lParam);
HWND hEdit;
HINSTANCE g_hInstance;

int WINAPI WinMain(HINSTANCE hInstance, HINSTANCE hPrevInstance,
    LPSTR lpCmdLine, int nCmdShow)
{
    WNDCLASSEX wc;
    HWND hwnd;
    MSG msg;
g_hInstance=hInstance;
    
    wc.cbSize        = sizeof(WNDCLASSEX);
    wc.style         = 0;
    wc.lpfnWndProc   = WndProc;
    wc.cbClsExtra    = 0;
    wc.cbWndExtra    = 0;
    wc.hInstance     = hInstance;
    wc.hIcon         = LoadIcon(NULL, IDI_APPLICATION);
    wc.hCursor       = LoadCursor(NULL, IDC_ARROW);
    wc.hbrBackground = (HBRUSH)(COLOR_WINDOW+1);
    wc.lpszMenuName  = NULL;
    wc.lpszClassName = g_szClassName;
    wc.hIconSm       = LoadIcon(NULL, IDI_APPLICATION);

    if(!RegisterClassEx(&wc))
    {
        MessageBox(NULL, "Couldn't Register Window", "Error!",
            MB_OK);
        return 0;
    }

    hwnd = CreateWindowEx(
        WS_EX_CLIENTEDGE,
        g_szClassName,
        "Subclassing example",
        WS_OVERLAPPEDWINDOW,
        190, 190,190,190,
        NULL, NULL, hInstance, NULL);

    if(hwnd == NULL)
    {
        MessageBox(NULL, "Couldn't create window", "Error!",
          MB_OK);
        return 0;
    }

    ShowWindow(hwnd, nCmdShow);
    UpdateWindow(hwnd);

    while(GetMessage(&msg, NULL, 0, 0) > 0)
    {
        TranslateMessage(&msg);
        DispatchMessage(&msg);
    }
    return msg.wParam;
}


LRESULT CALLBACK WndProc(HWND hwnd, UINT msg, WPARAM wParam, LPARAM lParam)
{
    switch(msg)
    {
	case WM_CREATE:

		hEdit=CreateWindow("Edit",
			"",
		WS_CHILD | WS_VISIBLE| WS_BORDER | ES_AUTOHSCROLL   ,
						30,30,60,30,hwnd,
							(HMENU)EDIT1,g_hInstance,NULL);

		
g_oldproc = (WNDPROC)SetWindowLong(hEdit, GWL_WNDPROC, (long)NewProc);
		break;

        case WM_CLOSE:
            DestroyWindow(hwnd);
        break;
        case WM_DESTROY:
            PostQuitMessage(0);
        break;
        default:
            return DefWindowProc(hwnd, msg, wParam, lParam);
    }
    return 0;
}



LRESULT CALLBACK NewProc (HWND hwnd, UINT msg, 
                             WPARAM wParam, LPARAM lParam)
{
	switch (msg)
	{

	case WM_CHAR:
		if(wParam!=8 && !isdigit(wParam))
			return 0;
		break;


	}

	return CallWindowProc (g_oldproc, hwnd, msg, wParam, lParam);
}