Q27327: Passing COMMON Variables from BASIC to C by Far Reference

Article: Q27327
Product(s): See article
Version(s): 4.00 4.00b 4.50
Operating System(s): MS-DOS
Keyword(s): ENDUSER | B_BasicCom S_C S_QuickC | mspl13_basic
Last Modified: 6-NOV-1989

The following example demonstrates how to pass COMMON variables from
compiled BASIC to Microsoft C by far reference.

This information about inter-language calling applies to 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.

For more information about passing other types of parameters between
BASIC and C, and a list of which BASIC and C versions are compatible
with each other, query in the Software/Data Library on the following
word:

   BAS2C

Code Example
------------

REM ===== BASIC PROGRAM =====

DECLARE SUB RCommon CDECL (_
            BYVAL p1o AS INTEGER,_
            BYVAL p1s AS INTEGER)
COMMON SHARED element1 AS INTEGER, element2 AS STRING * 20, _
              element3 AS SINGLE
element1 = 23
element2 = "DATE : " + DATE$ + CHR$(0)
element3 = 309.03
CALL RCommon(VARPTR(element1), VARSEG(element1))
END

/* ===== C ROUTINE ===== */

#include <stdio.h>
struct common_block{   /* structure that looks like the BASIC */
       int a;          /* common block                        */
       char b[20];
       float c;
};
void RCommon(pointer)
     struct common_block far *pointer;
 {
     printf("Element1 = %d\n",pointer->a);
     printf("Element2 = %s\n",pointer->b);
     printf("Element3 = %f\n",pointer->c);
 }

===== OUTPUT =====

Element1 = 23
Element2 = DATE : 02-02-1988
Element3 = 309.029999

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.