Thread: Going back to a main menu from anywhere

I have various menus in my program, and I would like the user to be able to press for example the key "ESC" at any moment so that he'd return to the main menu. I would know how to include this option in every menu (just adding one option at the end), but I want to be able to go back to the main menu at any moment. For example, if the user is entering new data for a new project, but he changes his mind, now he'd have to finish writing data (even if it useless).

I've had a look thgough the two books I have, and through the help file from the compiler (Turbo C++ 3.0) but I couldn't find anything.

It's not homeworking, just curiosity

Any simple ideas?

Well, that depends upon how the user enters data. If you are using a "high level" function like scanf() for this, then your options are quite limited and relatively complex. If however, you are doing your own string parsing (you are getting each and every individual key) then you simply put in an if testing for ASCII 27 (ESC) or whatever. I bet that doesn't help you much, because making your own scanf() is fairly complex too, but that's what I would do.

well, if you find out the scan code for something like F1 (you wouldn't want ESC) then you can use goto...I know it's not great programming proactice, but it's probably the simplest solution typing-wise.

I tried something like this once, what I did was to have the main menu at the beginning of main() then when I wanted to return to the main menu from deep inside the program I just called main()

Code:

if( ch == ESC)
     main();

This worked, but with some anomilies, like next time through it skipped part of the prog, I think this may have been due to data left in the prog somewhere(which I couldn't find). If you try this method let me know how you get on as I'd be interested to hear if you have the same problem.

You'll need to catch keystrokes. Basicly, you'll have to handle input a character at a time, and when they hit a "hotkey" or "enter", you invoke the correct command.

Something like:

Code:

c = getkeyfromuser();
switch(c)
{
   case ESCAPE: {flushbuffer( buffer ); mainmenu( ); break; }
   case ...
   default: addctobuffer(c, buffer);
}

You actually want a finite state machine. This is to say: you run a switch / loop around your whole program, and track the current "state". The state is used as the switch/case trigger, invoking the correct reaction. This is as I basicly described it above.

By the way, escape I believe is in decimal, 27. The keystroke for it may or may not be the same. At any rate, you have to monitor keystrokes, not line reads.


Quzah.

Let's see if I understand you. For example I have my main like this:

int
main(void)
{


MENU();

return (0);
}


So that thgrough the MENU() function I get to the program. If I include this line into a loop as quzah has described, would the program be "alert" waiting for the hotkey to be pressed while it's running?

I think I'll try to make a little program to check, so I'll post it tomorrow morning.

Thanks for the effort guys,

Well, I've been trying this morning to come up with something, but I can't get anything to work. I think it might be too much for me, so I'll keep on with simple functions by now.