Q27295: Passing BASIC SINGLE-Precision Array to C by Far Reference

Article: Q27295
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 example below demonstrates how to pass a single-precision array
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
------------

===== BASIC PROGRAM =====

DECLARE SUB FloatArray CDECL (_
            BYVAL p1 AS INTEGER,_
            BYVAL p2 AS INTEGER)
DEFINT A-Z
DIM i AS SINGLE
DIM array(10) AS SINGLE
CLS
FOR i = 1 TO 10
   array(i) = i + 100
NEXT i
'Array must be a FAR pointer, so offset and segment must be passed:
CALL FloatArray(VARPTR(array(0)), VARSEG(array(0)))
LOCATE 15, 1
PRINT "Back in BASIC"
FOR i = 1 TO 10
   PRINT i, array(i)
NEXT i
END

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

#include <stdio.h>
void FloatArray(array)
   float far *array;
 {
    int i;
    printf("Index         Value\n");
    for (i=0;i < 11; i++)
       {
         printf("  %d          %f\n",i,array[i]);
         array[i]=array[i]+100;
       };
 }

===== OUTPUT =====

Index         Value
  0          0.000000
  1          101.000000
  2          102.000000
  3          103.000000
  4          104.000000
  5          105.000000
  6          106.000000
  7          107.000000
  8          108.000000
  9          109.000000
  10          110.000000

Back in BASIC
 1             201
 2             202
 3             203
 4             204
 5             205
 6             206
 7             207
 8             208
 9             209
 10            210