How do I change main menu in application dynamically?

My experience is that users don't like it when controls (or menu items) appear and disappear while they're using the program. At the very most, they are just barely comfortable with items being disabled, but when things start disappearing/reappearing, they freak out. I'd rethink my interface if I were you.

If your target is to change the menu at compile time, the best is to create your menus with the resource editor, using the same ID for all of them, and using the Condition property of them (you find the Condition property on the Property window).

This way the resource editor generates an rc file with the #ifdef required to compile or not your menus depending on the resource compiler pre-processor macro that you put inside the Condition property.

Note that the pre-processor macro used by the resource compiler are not the same that the C/C++ compiler uses: you should define them on the Resource tab of your project properties.

Sorry.. My mistake.. I have 3 various menus in which I want to select during compiling application by passing a flag to the compiler, then the required menu will always be the main menu.

Neil