Q48206: Example of C Functions Returning Numeric Types to BASIC

Article: Q48206
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: 20-DEC-1989

The two programs shown below demonstrate how Microsoft C functions can
return common numeric types to BASIC.

This information about inter-language calling applies to QuickBASIC
Versions 4.00, 4.00b, 4.50 for MS-DOS, to Microsoft BASIC Compiler
Versions 6.00 and 6.00b for MS-DOS and MS OS/2, and to Microsoft BASIC
PDS Version 7.00 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 for the following
word:

   BAS2C

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

The following BASIC program is BFUNC.BAS, which invokes several C
functions, and prints out the values returned by the functions:

DECLARE FUNCTION cintfunc% CDECL ()
DECLARE FUNCTION clongfunc& CDECL ()
DECLARE FUNCTION cdoublefunc# CDECL ()
PRINT "Integer: "; cintfunc
PRINT "Long   : "; clongfunc
PRINT "Double : "; cdoublefunc

The following program is CFUNC.C, which contains several functions
called from BASIC. These functions return standard numeric types to
the calling BASIC program.

int cintfunc(void)        /* BASIC INTEGER */
{
   int theint = 32767;
   return(theint);
}

long clongfunc(void)      /* BASIC LONG */
{
   long thelong = 32769;

   return(thelong);
}

double cdoublefunc(void)  /* BASIC DOUBLE */
{
   double thedouble = 129381.123;
   return(thedouble);
}

To demonstrate these programs from an .EXE program, compile and link
as follows:

   BC BFUNC.BAS;
   CL /c /AM CFUNC.C;
   LINK /NOE BFUNC CFUNC;

BFUNC.EXE produces the following output:

   Integer:  32767
   Long   :  32769
   Double :  129381.123