"DialogProc not declared" error shown while it is definitely declared - c++

Question

I am building my first GUI.
The following is my code.
#include <windows.h>
#include "resource.h"
const char g_szClassName[] = "home";
LRESULT CALLBACK WndProc(HWND hwnd, UINT msg, WPARAM wParam, LPARAM lParam) {
switch(msg)
{
case WM_CLOSE:
DestroyWindow(hwnd);
break;
case WM_DESTROY:
PostQuitMessage(0);
break;
default:
return DefWindowProc(hwnd, msg, wParam, lParam);
}
return 0;
}
BOOL CALLBACK HomeDialogProc(HWND hwnd, UINT msg, WPARAM wParam, LPARAM lParam) {
switch (msg) {
case WM_COMMAND:
switch(LOWORD(wParam)){
case IDC_ABOUT:
CreateDialog(GetModuleHandle(NULL), MAKEINTRESOURCE(IDT_ABOUTDIALOG), hwnd, AboutDlgProc);
break;
}
break;
default:
return FALSE;
}
return FALSE;
}
BOOL CALLBACK AboutDlgProc(HWND hwnd, UINT Msg, WPARAM wParam, LPARAM lParam) {
switch(Msg)
{
case WM_COMMAND:
switch(LOWORD(wParam))
{
case IDC_DLG_EXIT:
DestroyWindow(hwnd);
break;
}
break;
default:
return FALSE;
}
return FALSE;
}
int WINAPI WinMain(HINSTANCE hInstance, HINSTANCE hPrevInstance, LPSTR lpCmdLine, int nCmdShow) {
WNDCLASSEX wc;
HWND hwnd;
HWND dialog;
MSG Msg;
wc.cbSize = sizeof(WNDCLASSEX);
wc.style = 0;
wc.lpfnWndProc = WndProc;
wc.cbClsExtra = 0;
wc.cbWndExtra = 0;
wc.hInstance = hInstance;
wc.hIcon = LoadIcon(GetModuleHandle(NULL), MAKEINTRESOURCE(IDI_MYICON));
wc.hCursor = LoadCursor(NULL, IDC_ARROW);
wc.hbrBackground = (HBRUSH) (COLOR_WINDOW + 1);
wc.lpszMenuName = MAKEINTRESOURCE(IDR_MYMENU);
wc.lpszClassName = g_szClassName;
wc.hIconSm = (HICON) LoadImage(GetModuleHandle(NULL), MAKEINTRESOURCE(IDI_MYICON), IMAGE_ICON, 16, 16, 0);
if (!RegisterClassEx(&wc)) {
MessageBox(NULL, "Window Registration Failed!", "Error!", MB_ICONEXCLAMATION | MB_OK);
return 0;
}
hwnd = CreateWindowEx(
WS_EX_CLIENTEDGE,
g_szClassName,
"Have faith, we will succeed",
WS_OVERLAPPEDWINDOW,
CW_USEDEFAULT, CW_USEDEFAULT, 800, 500,
NULL, NULL, hInstance, NULL);
if (hwnd == NULL) {
MessageBox(NULL, "Window Creation Failed!", "Error!", MB_ICONEXCLAMATION | MB_OK);
return 0;
}
ShowWindow(hwnd, nCmdShow);
UpdateWindow(hwnd);
dialog = CreateDialog(hInstance, MAKEINTRESOURCE(IDT_HOMEDIALOG), hwnd, HomeDialogProc);
if (!dialog) {
MessageBox(NULL, "Could not create Dialog", "CreateDialog", MB_ICONERROR);
return 1;
}
ShowWindow(dialog, nCmdShow);
UpdateWindow(dialog);
while (GetMessage(&Msg, NULL, 0, 0) > 0) {
TranslateMessage(&Msg);
DispatchMessage(&Msg);
}
return Msg.wParam;
}
I would like to briefly introduce what I want to do. I have embedded a dialog in the main window, so it "became part of the window". Then there is an About button in this dialog which is supposed to open the About dialog. I am really frustrated on the compilation error:
C:\Workspace_cpp\twodlg\main.cpp:28:97: error: 'AboutDlgProc' was not declared in this scope
CreateDialog(GetModuleHandle(NULL), MAKEINTRESOURCE(IDT_ABOUTDIALOG), hwnd, AboutDlgProc);
As you can see, I have clearly defined AboutDlgProc. On the other hand, from my readings, all the DialogProc functions do not necessarily need declaration to be functional. And finally, even after I explicitly put in the declaration statement, the error persists. Thank you so much for any help.

Answer 1

I solved it when I moved AboutDlgProc up. Answer was provided in comment by #MikeNakis, I am just closing the question.