🚀 go-pugleaf

> So strstr in C++ Builder is more than 200 times slower in this case. I 
> think, that C++ Builder is so slow, because this string is so large.
> My Turbo C++ is "a little broken" - when I create new console project, I 
> can't link it - it shows "unresolved externals" about CodeGuard files. I 
> have to enable CG in project options. In release, program is slow too.
> What is the reason? Do you have similar problem? 
> 
The reason is CodeGaurd. Codegaurd checks all your memory accesses which 
is slowing down the program. Try to get it to link without codeguard.

Eelke

"Julek" <julekmen@go2.pl> writes:

> take a look at this program:
>
> #include <stdio.h>
> #include <stdlib.h>
> #include <limits.h>
> #include <string.h>
> #include <time.h>
>
> int WezR()
> {
>  return (int)rand()*(int)rand()+(int)rand();

The return type of rand() already is int. Why the casts?

More importantly, the expression may overflow, in which case your
program has undefined behavior.

In particular, WezR() may very well return a negative value ...


> }
>
> int main(int argc, char* argv[])
> {
>  time_t TimeX,TimeX2;
>  time(&TimeX);
>  int D=10000000;
>  char *TTT=new char[D];
>
>  for(int a=0;a<D-1;++a)
>   TTT[a]='a';
>  for(int a=0;a<1000000;++a)

[make D const and change 1000000 to D/10, to err on the safe side]


>   TTT[WezR()%(D-1)]='b';

... and applying % doesn't make it non-negative; more undefined
behavior ...


>  TTT[D-1]=0;
>  time(&TimeX2);
>  printf("Preparation - %d\n",TimeX2-TimeX);
>  for(int a=0;a<1000;++a)
>  {
>   int NumerStart=WezR()%(D-1);
>   char *Start=TTT+NumerStart;

... and more here. This is where I stopped looking.

Try fixing your program and report back.

"Julek" <julekmen@go2.pl> wrote in msg 
news:46161b72@newsgroups.borland.com...

> int D=10000000;
> char *TTT=new char[D];

You have to delete array TTT

delete[] TTT;


I got

Preparation -0 or 1
finding - 0

_minas

------
"Only the virtue's conquests have certainty" Sofokleous Erephyle 

Thomas Maeder [TeamB] wrote:

>> #include <stdlib.h>

>>  return (int)rand()*(int)rand()+(int)rand();
>
>More importantly, the expression may overflow, in which case your
>program has undefined behavior.

Ummm, I think the maximum calculated value is 3FFF 8000, which is
positive, and doesn't overflow unless int is 16bit.

Replace rand() with RAND_MAX and you get
	RAND_MAX * RAND_MAX + RAND_MAX

For easier manual calculation:
	RAND_MAX * (RAND_MAX+1)
	7FFF * 8000 = 3FFF8000

Perhaps you were thinking of _lrand which returns a 31 bit value.

It must be the CodeGuard, my output of the program is,
even when I change the last for-loop to 100000 iterations:

Preparation - 0
Finding - 0

Bob Gonder <notbg@notmindspring.invalid> writes:

> Thomas Maeder [TeamB] wrote:
>
>>> #include <stdlib.h>
>
>>>  return (int)rand()*(int)rand()+(int)rand();
>>
>>More importantly, the expression may overflow, in which case your
>>program has undefined behavior.
>
> Ummm, I think the maximum calculated value is 3FFF 8000, which is
> positive, and doesn't overflow unless int is 16bit.

RAND_MAX is an implementation-defined value. The Standard doesn't
guarantee that the quoted expression doesn't overflow.

U�ytkownik "Koen" <koen@ha.com> napisa� w wiadomo�ci
news:Xns990AA2E742888koenhacom@207.105.83.66...
> It must be the CodeGuard,

Yes, it's the real reason :)Thank you.