How to Create a Near String when Using Far Strings (85265)

MORE INFORMATION

The following example Basic program creates a near string descriptor and calls a sample C function that expects to receive a near string descriptor:

Example Program

TYPE descriptortype     ' This TYPE statement defines a near string
                        ' descriptor.
    length AS INTEGER
    offset AS INTEGER
END TYPE

DECLARE SUB stringnear CDECL (descript AS descriptortype)

DIM descriptor AS descriptortype
CLS
DIM tempstring AS STRING * 255  ' This string must be one character
                                ' longer than the maximum length you
                                ' expect your string to be.
a$ = "It Works!!" + CHR$(0)     ' Some library routines expect a NUL
                                ' appended to the end of the string.
descriptor.length = LEN(a$)
tempstring = a$
descriptor.offset = VARPTR(tempstring)' Get the address of the string.
PRINT "In basic length of the string is "; LEN(a$)
CALL stringnear(descriptor)' Call the C subprogram.
PRINT: PRINT: PRINT
END
				

The following C function receives a near string descriptor as a parameter:

#include <stdio.h>
struct descriptor_struct  /* Defines the near string descriptor. */ 
{
  int length;
  char *offset;
};

void stringnear(struct descriptor_struct *descriptor){
  printf("In C length of the string is: %d \n\n", descriptor->length);
  printf("The string text is : %s \n\n", descriptor->offset);
}
				

Compile the Basic program above with:

   BC /FS Basic.BAS;
				

Compile the C program above with:

   CL -c -AM  C.C
				

(NOTE: The C compiler used to compile this program must be compatible with Basic PDS.)

Link the modules together with:

   LINK /NOE Basic.OBJ+C.OBJ,,, BRT71EFR.LIB+MLIBCE.LIB;
				

For more information about calling C from Basic, query on the following word in the Microsoft Knowledge Base: