Q43563: Function MENU%() Fails in Hergert’s "QuickBASIC, 2nd Edition"

Article: Q43563
Product(s): See article
Version(s): 3.00 4.00 4.00b 4.50
Operating System(s): MS-DOS
Keyword(s): ENDUSER | docerr B_BasicCom | mspl13_basic
Last Modified: 14-DEC-1989

The MENU%() function in the Microsoft Press book "Microsoft
QuickBASIC, Second Edition" by Douglas Hergert will fail if it is
coded without the variables "true%" and "false%" defined in the main
program. If these lines are not included, the program will eventually
enter an infinite loop that can only be exited with CTRL+BREAK.

The program can be found on Pages 68-71 in Hergert's book. This
program, which is designed to be incorporated into your program,
displays a menu box with menu options and returns a value equal to
your selection. The book assumes that you have defined the variables
"true%" and "false%" in the title of your main program. This is a
documentation omission.

This information applies to Microsoft QuickBASIC Versions 3.00, 4.00,
4.00b, and 4.50, to Microsoft BASIC Compiler Versions 6.00 and 6.00b,
and to Microsoft BASIC PDS Version 7.00.

The workaround for this problem is to add one of the following lines
of code to the beginning of the program:

   false% = 0 : true% = NOT false%
   true% = -1 : false% = NOT true%

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