Q51411: How to Use SEG Keyword with Arrays in DECLARE and CALLs

Article: Q51411
Product(s): See article
Version(s): 4.00 4.00b 4.50
Operating System(s): MS-DOS
Keyword(s): ENDUSER | SR# S891120-129 B_BASICCOM | mspl13_basic
Last Modified: 12-DEC-1989

The examples shown below demonstrate how to use the SEG keyword with
arrays. The SEG keyword may be used in either a DECLARE statement or a
CALL statement when calling a non-BASIC routine, and is used to pass
both the segment and offset of a variable (which corresponds to
passing a far address).

This information applies to Microsoft QuickBASIC Versions 4.00, 4.00b,
and 4.50 for MS-DOS and to Microsoft BASIC Compiler Versions 6.00 and
6.00b for MS-DOS and MS OS/2.

When using SEG in the DECLARE statement to pass the far address of an
array to a non-BASIC routine, the array should be specified as a
simple variable without using the array notation, as follows:

   DECLARE SUB TEST(SEG a AS INTEGER)
   DIM a(10) AS INTEGER
   TEST(a(0))

A compilation error will occur if the array is DECLAREd using array
notation as follows:

   DECLARE SUB TEST(SEG a() AS INTEGER)
   DIM a(10) AS INTEGER
   TEST(a(0))

Inside the QuickBASIC QB.EXE environment, the error message "Expected:
, or )" will be displayed for the above DECLARE statement. When
compiled from the BC.EXE command line, the following two error
messages display:

   "Syntax error"
   "Formal parameter specification illegal"

When using SEG in an explicit CALL statement there should not be a
DECLARE statement. Explicitly using the CALL keyword (instead of using
an implied call) takes the place of the DECLARE statement. The correct
syntax is as follows:

   DIM a(10) AS INTEGER
   CALL TEST(SEG a(0))

If a DECLARE statement is used with an explicit CALL statement that
uses SEG, the error "Parameter type mismatch" displays.

THE INFORMATION PROVIDED IN THE MICROSOFT KNOWLEDGE BASE IS PROVIDED "AS IS" WITHOUT WARRANTY OF ANY KIND. MICROSOFT DISCLAIMS ALL WARRANTIES, EITHER EXPRESS OR IMPLIED, INCLUDING THE WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE. IN NO EVENT SHALL MICROSOFT CORPORATION OR ITS SUPPLIERS BE LIABLE FOR ANY DAMAGES WHATSOEVER INCLUDING DIRECT, INDIRECT, INCIDENTAL, CONSEQUENTIAL, LOSS OF BUSINESS PROFITS OR SPECIAL DAMAGES, EVEN IF MICROSOFT CORPORATION OR ITS SUPPLIERS HAVE BEEN ADVISED OF THE POSSIBILITY OF SUCH DAMAGES. SOME STATES DO NOT ALLOW THE EXCLUSION OR LIMITATION OF LIABILITY FOR CONSEQUENTIAL OR INCIDENTAL DAMAGES SO THE FOREGOING LIMITATION MAY NOT APPLY.

Copyright Microsoft Corporation 1986-2002.