[AccessD] Array faster in DLL?

Hi Shamil

I just read your post following this, and your conclusion about C# seems to be true.

Your results from C++ is an eye-opener. I hardly can believe that speed improvement!
But for a true comparison, could I persuade you to compile it to an DLL and call that from VB(A) the same way I did with the DLL compiled in FreeBASIC?
You would probably need 10^7 loops or - if you measurement holds - 10^8 loops.

/gustav


>>> shamil at users.mns.ru 31-10-2005 09:40:17 >>>
Hi Gustav,

With switched off array bounds check and integer overflow check your
sample code runs in less than 1 second when in VB6 bActiveX dll.

Similar code in C++(VS.NET 2003) runs instantaneously.

C++ allows to measure time when 10^6 cycles are additionally cycled
10^7 times!

Below is sample C++ code. Maybe I did make some mistakes -
10^7 * 10^6 loops in just two seconds looks incredible speed
gain under C++ - these are 989,999,010,000,000 cycles...

And in 19 seconds 9,899,990,100,000,000 cycles can be executed.

long ArrayTimeLocal(long lngLoopMax, long& lngTotalCnt);
int _tmain(int argc, _TCHAR* argv[])
{
 long dblStart;
 long dblStop;
 long lngResult;
 long lngCnt = 0;
 __int64 totalCnt = 0;
 time(&dblStart);
 for (int i = 1; i<=10000000; i++) {
  lngResult = ArrayTimeLocal(1000000, lngCnt);
  totalCnt += ((__int64)lngCnt);
  if ((i % 1000000) == 0)
   printf("Result = %ld, Counter = %I64d\n",
    lngResult, totalCnt);
 }
    time(&dblStop);
 lngResult = (long)difftime(dblStop,dblStart);
 printf("Final Result = %ld, Final Counter = %I64d\n",
     lngResult, totalCnt);
}

long ArrayTimeLocal(long lngLoopMax, long& lngTotalCnt) {
  const long lngItems = 100;
  long alngTmp[lngItems-1][1];
  long lngLoop;
  long lngItem;
  long lngResult;
  long lngSeconds;
  long dblStart;
  long dblStop;

  lngTotalCnt = 0;
  time(&dblStart);
  for (lngLoop=1; lngLoop < lngLoopMax; lngLoop++) {
   for (lngItem=1; lngItem < lngItems; lngItem++) {
  alngTmp[lngItem-1][0] = lngLoop * 10;
  if (alngTmp[lngItem-1][0] / 10 == 100) lngResult = 1;
  else lngResult = 0;
  lngTotalCnt++;
   }
  }
  time(&dblStop);
  lngSeconds = (long)difftime(dblStop,dblStart);
  return lngSeconds;
}

And here is result of this code test run:

Result = 0, Counter = 98999901000000
Result = 0, Counter = 197999802000000
Result = 0, Counter = 296999703000000
Result = 0, Counter = 395999604000000
Result = 0, Counter = 494999505000000
Result = 0, Counter = 593999406000000
Result = 0, Counter = 692999307000000
Result = 0, Counter = 791999208000000
Result = 0, Counter = 890999109000000
Result = 0, Counter = 989999010000000
Final Result = 2, Final Counter = 989999010000000

Shamil