Re: TextOut() to a DialogBox ???

"Liviu" <lab2k1@gmail.c0m>
Wed, 24 Mar 2010 20:10:19 -0500
"Peter Olcott" <> wrote in message

"Geoff" <geoff@invalid.invalid> wrote in message

On Wed, 24 Mar 2010 15:39:26 -0500, "Peter Olcott"
<> wrote:

Here is an interesting note that I don't understand. A
slight revision (to make it a little less CPU intensive,
thus more memory intensive) only actually achieves 21 MB per second
of the 12 GB / second maximum RAM speed.
(RAM speed reported by MemTest86).

const uint32 size = 100000000;
std::vector<uint32> Data;
uint32 Max = 0x3fffffff;

void Process() {
 clock_t finish;
 clock_t start = clock();
 double duration;
 uint32 num;
   for (uint32 N = 0; N < Max; N++)
     num = Data[num];
  finish = clock();
  duration = (double)(finish - start) / CLOCKS_PER_SEC;
  printf("%4.2f Seconds\n", duration);

Another thing that I don't understand is that it crashes
     num = Data[num];
is replaced by
     num = Data[N];

Two bugs exist.

1. You never initialize num [...]


Which gives a C4700 compiler warning, btw. Assuming you somehow
overlooked, or chose to ignore that, the debugger would have stopped
on the offending line with all the necessary clues to figure out why.

You _did_ run it under the debugger before asking for help on usenet
and waiting many hours to learn the all too obvious answer... right?

2. You never resize the vector space "Data" before you attempt to
access it.


Wrong. (reserve() has almost the same effect as resize() )

int main() [...]

Geoff was replying to your earlier post, which showed no 'reserve'.
You only included the main() part and 'reserve' in the later followup.


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