Passing Basic Double-Precision Array to C by Far Reference (27290)

SUMMARY

The example below demonstrates how to pass a double-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.

MORE INFORMATION

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 Microsoft Knowledge Base using the following word:

BAS2

Code Example

REM ===== Basic PROGRAM =====

DECLARE SUB DoubleArray CDECL (_
            BYVAL p1 AS INTEGER,_
            BYVAL p2 AS INTEGER)
DEFINT A-Z
DIM i AS DOUBLE
DIM array(10) AS DOUBLE
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 DoubleArray(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 DoubleArray(array)
   double far *array;
 {
    int i;
    printf("Index         Value\n");
    for (i=0;i < 11; i++)
       {
         printf("  %d          %lf\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