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