When is this part of code declared?

Question

I am following the tutorial on modeless_dialogs.html about dialog boxes. In an example, when it shows the code CreateDialog(GetModuleHandle(NULL), MAKEINTRESOURCE(IDD_TOOLBAR), hwnd, ToolDlgProc);, at the end it shows ToolDlgProc. And I have one question. When is this defined? How can I implement this? What do I have to add to define something like that?

Answer 1

I have fixed the error, by calling BOOL CALLBACK right below where it declared the About function. Then, I added a return value to it. The code worked without errors! The dialog box does not open, but that is not related to this issue.

Answer 2

I have fixed the error, by calling BOOL CALLBACK right below where it declared the About function. Then, I added a return value to it. The code worked without errors! The dialog box does not open, but that is not related to this issue.

Answer 3

I have fixed the error, by calling BOOL CALLBACK right below where it declared the About function. Then, I added a return value to it. The code worked without errors! The dialog box does not open, but that is not related to this issue.