From: "News Reader" <nospam AT aol DOT com>
Newsgroups: comp.os.msdos.djgpp
Subject: Re: Newbie: multidimensional arrays problem
Date: Thu, 28 Aug 2003 21:15:27 +0200
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To: djgpp AT delorie DOT com
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Reply-To: djgpp AT delorie DOT com

You can leave your arrays inside the main() function as long as
they are declared static. The following is an example of your
program adapted to C (C++ could be arranged accordingly):


int main (int argc, char **argv)
{
  int x,y;
  puts(" currently here\n");  // you won't need this anymore   ; )

  #define Xmax 1200  // 'const int' does not work with static arrays
  #define Tmax 51

  static double price[Tmax][Xmax+1];
  static double reslevel[Tmax][Xmax+1];

// lots of code that doesn't involve price or reslevel

// I am just doing something with the arrays here,  because ...
// ... the optimizer might not generate any code otherwise:

  for (x=0; x<=Xmax; x++) for (y=0; y<Tmax; y++) {
    price[y][x]=x+y; reslevel[y][x]=x-y;
  }
  for (n=0,x=0; x<=Xmax; x++) for (y=0; y<Tmax; y++) {
    n+=price[y][x]-reslevel[y][x];
  }
  printf("\nn:%d\n\n",n);
  return 0;
}

Remark: static arrays are not using any stack space, therefore
the program should work without problems.


"Tom Weston" <tomweston_usenet AT yahoo DOT com> wrote in message
news:87752c88 DOT 0308270034 DOT 646465b AT posting DOT google DOT com...
> I'm quite a novice with c++ so this is probably more a language
> issue than a compiler/system one but I've been writing a program
> and have just included some multidimensional arrays that make
> for a strange effect that I can't explain.
>
> As the program currently stands it looks i outline like this
>
> int main()
> {
>
> cout << " currently here\n";
>
> const int xmax=1200;
> const int tmax=51;
>
> double price[tmax][xmax+1];
> double reslevel[tmax][xmax+1];
>
> // lots of code that doesn't involve price or reslevel
>
> return 0;
>
> }
>
> This compiles and when run doesn't print anything.
> If I comment out the two lines dimensioning the multi-dim
> arrays, it compiles and runs fine.
> If I change the data type of the arrays to int or float,
> it compiles OK and runs fine.
>
> This seems a bit bizarre to me, but as I say, I'm not experienced
> with C++.
>
> Any ideas?
>
> Many thanks,
> Tom