From: Andreas Dorn <adornno1 AT web DOT de>
Newsgroups: comp.os.msdos.djgpp
Subject: Re: Large Arrays
Date: Fri, 06 Jul 2001 00:42:27 +0200
Organization: University of Heidelberg, Germany
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References: <3B447193 DOT E7BA25AB AT ix DOT urz DOT uni-heidelberg DOT de> <7263-Thu05Jul2001212841+0300-eliz AT is DOT elta DOT co DOT il>
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Eli Zaretskii wrote: 
> > From: Andreas Dorn <adorn AT ix DOT urz DOT uni-heidelberg DOT de>
> > I need a really large array for a matrix (~100 MB).
> > With linux/unix and gcc that worked fine, but with dos/windows this
> > never worked. Even with 256MB RAM and "small" arrays (<5MB) it didn't
> > work.
> >
> > The initialisation of the array looks like this:
> >
> > int main(void)
> > {
> >   const int Dimension=5000;
> >
> >   float TheMatrix[Dimension][Dimension];
> >   int i,j;
> 
> Your program is blowing up the run-time stack, which by default is
> only 512KB large.  See section 15.9 of the DJGPP FAQ list for more
> details.
> 
> > - I don't have much experience with dos/windows compilers. What is the
> > reason for the memory-problems? And how much memory do I get for an
> > array under win3.11, win95, ..?
> 
> The amount of available memory can be seen by running the go32-v2
> program with no arguments.  A typical Windows system lets you use at
> least 64MB of memory; if you have more than 64MB physical memory
> installed, Windows will let you use up to the amount of the installed
> memory.
> Chapter 15 of the FAQ has more about this.
> 
> > - Is there an easy solution (a compiler option or something) to get a
> > working array?  (option: -WA <working array> :-))
> 
> You can stubedit the executable for a larger stack, or you can
> allocate the array at run time with malloc.  Again, the FAQ has the
> details.

Thank you for the information. I only have to check now what happens if
I use a lot of swap-space... but I think there'll be no trouble.

Andreas Dorn