Newsgroups: comp.os.msdos.programmer
Path: utzoo!utgpu!cunews!ajai
From: ajai@sce.carleton.ca (Ajai Sehgal)
Subject: Huge Arrays in Turbo C++
Message-ID: <ajai.653231857@talos.sce.carleton.ca>
Sender: news@ccs.carleton.ca (news)
Organization: Carleton University, Ottawa, Canada
Distribution: comp
Date: 13 Sep 90 13:17:37 GMT

As a follow up to my last question, after further experimentation I discovered
that if two separate arrays are declared as huge with exactly the same number
of elements, they are assigned the same start address and become essentially
the same array with different names. If I alter the size of the second array
by even one element, the two arrays are completely different and held in
different memory locations. This seems to me to be a compiler bug, one that the
latest Borland patch doesn't take care of.

example:	float huge array[1024][1024];
		float huge array2[1025][1024];
                                  ^^^^^
		works just fine , array and array2 are refer to different
		memory locations.

example2:	float huge array[1024][1024];
		float huge array2[1024][1024];

		does not work , array2 is effectively a copy of array and any
		values written to array also appear in the same locations in
		array2.

Note: the above problem does not appear to happen if the array size is smaller
      than 512 x 512.

	The second discovery I made is that huge arrays work just fine when
declared within a function as a local. When I tried to declare them as Globals
outside of Main() the program compiled just fine but hung the system half way 
through the linking process. (work just fine not including the problem describedabove). Being new to C , and C++ the above strikes me as being odd. Has anyone
out there experienced similar problems, if not , what am I doing wrong? Borland's manuals are less than clear and the latest books on C++ don't help either.
Any help would be greatly appreciated.

Regards, Ajai. (ajai@sce.carleton.ca)