dialog box creation in windows - c++

Question

I am running the following to create a dialog box in windows. when I run it I get the follwoing error:
Error 1 error C2065: 'IDD_DLGFIRST' : undeclared identifier
Here is the code:
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_DLGFIRST),
hWnd, reinterpret_cast<DLGPROC>(DlgProc));
return FALSE;
}
LRESULT CALLBACK DlgProc(HWND hWndDlg, UINT Msg, WPARAM wParam, LPARAM lParam)
{
switch(Msg)
{
case WM_INITDIALOG:
return TRUE;
case WM_COMMAND:
switch(wParam)
{
case IDOK:
EndDialog(hWndDlg, 0);
return TRUE;
}
break;
}
return FALSE;
}
//---------------------------------------------------------------------------
I do know that there are resource files but I haven't understood that very well.
could someone help me out to resolve this error please.

Answer 1

You need to define the symbol both in the resource file, as well as the file that calls MAKEINTRESOURCE. usually it's done via a common header file that you #include in both places (for instance #include resource.h in resource.rc and main.cpp).
And in the resource.h you put #define IDD_DLGFIRST 1 for example. Just make sure that the number is unique across resources.
EDIT:
As an example:
resource.h
#define IDD_DLGFIRST 1001
#define IDC_STATIC 1002
yourapp.rc
#include <windows.h>
#include "resource.h"
IDD_DLGFIRST DIALOGEX 0, 0, 170, 62
STYLE DS_SETFONT | DS_MODALFRAME | DS_FIXEDSYS | WS_POPUP | WS_CAPTION | WS_SYSMENU
CAPTION "My dialog"
FONT 8, "MS Shell Dlg"
BEGIN
LTEXT "My first dialog box, Version 1.0",IDC_STATIC,42,14,114,8,SS_NOPREFIX
DEFPUSHBUTTON "OK",IDOK,113,41,50,14,WS_GROUP
END
yourapp.cpp
#include <windows.h>
#include "resource.h"
INT_PTR CALLBACK DlgProc(HWND hWnd, UINT Msg, WPARAM wParam, LPARAM lParam);
INT WINAPI WinMain(HINSTANCE hInstance, HINSTANCE hPrevInstance,
LPSTR lpCmdLine, int nCmdShow)
{
//Open dialog box
DialogBox(hInstance, MAKEINTRESOURCE(IDD_DLGFIRST), HWND_DESKTOP, DlgProc);
return 0;
}
INT_PTR CALLBACK DlgProc(HWND hWndDlg, UINT Msg, WPARAM wParam, LPARAM lParam)
{
switch(Msg)
{
case WM_INITDIALOG:
return TRUE;
break; //Don't forget about the break;
case WM_COMMAND:
switch(wParam)
{
case IDOK:
EndDialog(hWndDlg, 0);
return TRUE;
}
break;
}
}