🚀 go-pugleaf

"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.