Path: utzoo!utgpu!jarvis.csri.toronto.edu!mailrus!purdue!mentor.cc.purdue.edu!j.cc.purdue.edu!pur-ee!pur-phy!murphy
From: murphy@pur-phy (William J. Murphy)
Newsgroups: comp.sys.amiga.tech
Subject: Programming multiple Menu Selections
Message-ID: <2124@pur-phy>
Date: 9 Apr 89 22:02:13 GMT
Reply-To: murphy@newton.physics.purdue.edu (William J. Murphy)
Organization: Purdue Univ. Physics Dept., W. Lafayette, IN
Lines: 36


I have been trying to figure out why I have a bug in a program of mine
which uses/supports multiple menu selections.  I have 2 menus, one with one
item, the other with two items. The FIRST time that I select Menu1 Item1,or
Menu2 Item2,
I get locked into a loop with number = 0.  The FIRST time that I select Menu2
Item1, everything from then on works fine.

I have isolated the problem as what is being returned by the function
number = ItemAddress(main_menu[0], number)->NextSelect;

number is intially given a value from
message = (struct IntuiMessage *)GetMsg(window->UserPort);
class   = message->Class;
code    = message->Code;
switch(class)
{
    case MENUPICK:
        handle_main_menu(code);
	break;
}

handle_main_menu(number)

From what I have discerned from Mortimore, if number is not a valid 
menuNumber then ItemAddress will return a NULL.  Is it correct to trap
for this potential error condition?  Maybe something like this?

if ((number = ItemAddress(main_menu[0], number)-NextSelect) == NULL)
    number = MENUNULL;

I use (number != MENUNULL) as a conditional test in a while loop.

Finally, I guess I am asking how do others support multiple menu selections
and is what I am doing flawed.
Bill Murphy