Q28283: It Is Illegal to Pass a CONST Type Constant in COMMON

Article: Q28283
Product(s): See article
Version(s): 6.00 6.00b 7.00 | 6.00 6.00b 7.00
Operating System(s): MS-DOS | OS/2
Keyword(s): ENDUSER | | mspl13_basic
Last Modified: 2-FEB-1990

A user-defined CONST constant cannot be passed in COMMON.

CONST constants never need to be passed in COMMON since you can put
the CONST definitions in a $include file to include for use in any
desired module.

A given user-defined CONST constant is local to each separately
compiled module, and can be used throughout a given source file.

The following is an example of illegally passing a CONST type symbol
in COMMON. In the QB.EXE environment that comes with Microsoft BASIC
Compiler Versions 6.00 and 6.00b or in the QBX.EXE environment
supplied with Microsoft BASIC Professional Development System (PDS)
Version 7.00, the following program correctly gives a "duplicate
definition" error on x in the COMMON SHARED:

   CONST x = 5
   COMMON SHARED x, y, z   ' "duplicate definition" error for x
   TYPE person
     test AS STRING * x
   END TYPE
   DIM joe AS person

Please note that when you use STRING * x, x must be a CONST type or a
numeric constant, according to the "Microsoft QuickBASIC 4.0: BASIC
Language Reference" manual on Page 430.

The following shows how the above program can be modified to work
correctly:

   CONST x = 5
   COMMON SHARED y, z
   TYPE person
     test AS STRING * x
   END TYPE
   DIM joe AS person

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