Q27289: Passing BASIC Variable-Length String to C by Near Reference

Article: Q27289
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 is an example of how to pass a BASIC variable-length
string variable by near reference to a Microsoft C routine.

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 StringNear CDECL (_
        BYVAL p1o AS INTEGER,_
        SEG p3 AS INTEGER)
CLS
a$ = "This is a test" + CHR$(0)
CALL StringNear(SADD(a$), LEN(a$))
END

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

#include <stdio.h>
void StringNear(a,len)
   char near *a;
    int *len;
 {
    int i;
    printf("The string is : %s \n\n",a);
    printf(" Index       Value       Character\n");
    for (i=0;i < *len; i++)
       {
         printf("  %2d          %3d            %c\n",i,a[i],a[i]);
       };
 }

===== OUTPUT =====

The string is : This is a test

 Index       Value       Character
   0           84            T
   1          104            h
   2          105            i
   3          115            s
   4           32
   5          105            i
   6          115            s
   7           32
   8           97            a
   9           32
  10          116            t
  11          101            e
  12          115            s
  13          116            t
  14            0