Receive a cluster from a dll function

Question

Hi,
I have a function in a DLL which returns a C struct.  I want to know how can I receive a cluster from a CLFN?
struct info:
struct typedata{
int a;
int b;
const char * c;
int d;
int e;
}data;
function call:
const typedata * hostinfo(int param);
Solved!
Go to Solution.

Answer 1

LVCoder wrote:
Thanks a lot both of you for letting me know about my dumb assumption that 2 different processes can use the same memory space.
Anyways, I figured out the problem with my code that was reading the double value. 
the DLL function returns the address of the struct which has 5 elements.
struct test {
int a;
int b;
int c;
double d;
double e;
suppose the address I receive is 10
address of test->a = 10
address of test->b = 14
address of test->c = 18
address of test->d = 26 // I was refering it as address 22. but I forgot that I was on a 64 bit machine and that the OS will allocate the whole memory address for a double and won't utilize the 4 bytes left in the previous memory address. 
thanks!
That has nothing to do with the bitness of your CPU or the OS. It is only dependent on the compiler alignment setting when you compile your DLL. Microsoft Compilers use a default alignment of 8 bytes. That means every variable or element inside a cluster will be aligned to the smaller one of either its own size or the default alignment.
You can change the compiler alignment either with a compiler switch or an explicit #pragma iin your source code where you declare the variables or structure typedefs.
Rolf Kalbermatter
CIT Engineering Netherlands
a division of Test & Measurement Solutions