Article Q68663
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Passing Basic Numeric Arrays from Basic to C and Back to Basic - Q68663
The following example demonstrates how to pass numeric arrays from
compiled BASIC to Microsoft C then back to BASIC using BASIC's "by
reference" calling convention.
More Information:
The example listed below differs from the other Basic-to-C
array-passing examples in that the example below lets you pass array
data from BASIC to C then back to BASIC. Other Basic-to-C examples
pass array data from Basic to C, but not back to Basic.
Code Example
============
Compile and link the sample programs below as follows:
BC /O ByRefB.BAS ;
CL /c /W3 /AM ByRefC.C
LINK /NOE ByRefB ByRefC ;
ByRefB.BAS
----------
' Declare the BASIC and C routines to use the same calling
' convention. In this case we want the default Basic "BY REFERENCE"
' calling convention.
DECLARE SUB BTest (Array1%(), Array2!(), Array3#(), Array4&())
DECLARE SUB CTest (Array1%(), Array2!(), Array3#(), Array4&())
' $STATIC
DIM A%(10), B!(10) ' Define some STATIC data in "DGROUP".
' $DYNAMIC
DIM C#(10), D&(10) ' And, some DYNAMIC data.
CLS
FOR i% = 0 TO 10 ' Initialize the arrays.
A%(i%) = i%
B!(i%) = .5 * i%
C#(i%) = 1.5 * i%
D&(i%) = i% * i%
NEXT i%
CTest A%(), B!(), C#(), D&()
PRINT A%(10), B!(10), C#(10), D&(10)
END
SUB BTest (Array1%(), Array2!(), Array3#(), Array4&())
PRINT
FOR i% = 0 TO 10
PRINT Array1%(i%), Array2!(i%), Array3#(i%), Array4&(i%)
NEXT i%
END SUB
ByRefC.C
--------
#include <stdio.h>
/**
** Use "typedef" to reduce complexity/readability of code.
**
** BASIC's BY REFERENCE is a near handle to a far pointer for the
** actual data of numeric arrays.
**/
typedef int far * near * HInt ;
typedef long far * near * HLng ;
typedef float far * near * HSng ;
typedef double far * near * HDbl ;
/**
** Define the BASIC routine as a "standard BASIC" call so the
** parameters will be the same.
**/
extern void pascal BTest ( HInt, HSng, HDbl, HLng ) ;
/**
** Define our C routine as a "standard BASIC" routine so we look
** like BASIC. This simplifies the parameter passing since we
** all look the same on the stack.
**/
void pascal CTest (HInt IntArray, HSng SngArray,
HDbl DblArray, HLng LngArray)
{
int j, i;
printf ("\Original Array Values\") ;
BTest ( IntArray, SngArray, DblArray, LngArray ) ;
for (i = 0, j = 10; i < 6; i++, j--)
{
(*IntArray)[i] = (*IntArray)[j] ;
(*LngArray)[i] = (*LngArray)[j] ;
(*SngArray)[i] = (*SngArray)[j] ;
(*DblArray)[i] = (*DblArray)[j] ;
}
printf ("\Modified Array Values\") ;
BTest ( IntArray, SngArray, DblArray, LngArray ) ;
printf ("\Modified Last Array Elements\") ;
(*IntArray) [10] = (int) 3 ;
(*SngArray) [10] = (float) 4.45 ;
(*DblArray) [10] = (double) 30.303 ;
(*LngArray) [10] = (long) 445 ;
}
Program Output
==============
Original Array Values
0 0 0 0
1 .5 1.5 1
2 1 3 4
3 1.5 4.5 9
4 2 6 16
5 2.5 7.5 25
6 3 9 36
7 3.5 10.5 49
8 4 12 64
9 4.5 13.5 81
10 5 15 100
Modified Array Values
10 5 15 100
9 4.5 13.5 81
8 4 12 64
7 3.5 10.5 49
6 3 9 36
5 2.5 7.5 25
6 3 9 36
7 3.5 10.5 49
8 4 12 64
9 4.5 13.5 81
10 5 15 100
Modified Last Array Elements
3 4.45 30.303 445