Undefined Var Use, Not Compiling

I am trying to monitor an EDIT control to see if the number 7 was entered

Here is my code.

2 questions, first AM I Definining the number 7 correctly

second, it's not compiling, something about undefined variable. i am fairly new to c++ and can't get this work. It should simply MessageBox when the user enters 7 in the field.

It doesnt

#include <windows.h>


#include "resource.h"

HHOOK g_hhk;
HWND g_hEdit;
const byte VK_7 = (byte)0x37;


LRESULT CALLBACK GetMsgProc(
    int code,
    WPARAM wParam,
    LPARAM lParam
)
{
    if (0 > code || PM_NOREMOVE == wParam) return CallNextHookEx(g_hhk,code,wParam,lParam);

    MSG* pmsg = (MSG*) lParam;

    if (pmsg->message == WM_KEYDOWN) { // this one is for us

        if (pmsg->hwnd == g_hEdit && pmsg->wParam == VK_7) { // '7' has been pressed if the monitored edit control

            // ---> ACTION!
            MessageBox(NULL, "The number was pressed!", "Notice", MB_OK);
        }
    }

    return CallNextHookEx(g_hhk,code,wParam,lParam);
}

void InitMonitoring(HWND hEdit) {

    h_hEdit = hEdit;

    g_hhk = SetWindowsHookEx(WH_GETMESSAGE,GetMsgProc,NULL,GetCurrentThreadId());
}

void StopMonitoring() {

    UnhookWindowsHookEx(g_hhk);
}
                                            


//---------------------------------------------------------------------------
HWND hWnd;
LRESULT CALLBACK DlgProc(HWND hWnd, UINT Msg, WPARAM wParam, LPARAM lParam);
//---------------------------------------------------------------------------

INT WINAPI WinMain(HINSTANCE hInstance, HINSTANCE hPrevInstance,
				   LPSTR lpCmdLine, int nCmdShow)
{
	DialogBox(hInstance, MAKEINTRESOURCE(IDD_DIALOG1),
	          hWnd, reinterpret_cast<DLGPROC>(DlgProc));

	return FALSE;
}
//---------------------------------------------------------------------------
LRESULT CALLBACK DlgProc(HWND hWndDlg, UINT Msg, WPARAM wParam, LPARAM lParam)
{
	switch(Msg)
	{
	case WM_INITDIALOG:
         InitMonitoring(GetDlgItem(hwndDlg,IDC_EDIT1));
		return TRUE;

	case WM_COMMAND:
		switch(wParam)
		{
		case IDOK:
             
			EndDialog(hWndDlg, 0);
			
			
			
			
			return TRUE;
		}
		break;
	}

	return FALSE;
}
//---------------------------------------------------------------------------
                                  

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Please help!