Path: utzoo!utgpu!news-server.csri.toronto.edu!cs.utexas.edu!swrinde!zaphod.mps.ohio-state.edu!rpi!quimby
From: quimby@itsgw.rpi.edu (Tom Stewart)
Newsgroups: comp.lang.c++
Subject: Re: TC++ problem w/huge arrays of struct?
Keywords: TC++; arrays; pointers; struct;
Message-ID: <8#H^*~&@rpi.edu>
Date: 15 Dec 90 16:30:16 GMT
References: <678@roo.UUCP> <13035@milton.u.washington.edu>
Organization: Rensselaer Polytechnic Institute, Troy NY
Lines: 41
Nntp-Posting-Host: madoka.its.rpi.edu

A couple of corrections are in order.  In a previous post I stated that
static data in TC++ is limited to 64k.  This is incorrect, as of TC++
v1.0 -- Static data >64k, including arrays >64k, is supported if explicitly
declared as 'far' or 'huge', respectively. 

In article <678@roo.UUCP> barbarin@Xerox.com (Mike Barbarino) writes:
>I'm having some problems with TC++ :

> const DBSIZE = 31000;
> long memsize;
> struct weights {
>    unsigned long   x;
>    unsigned long   y;
>    };
>
> memsize = DBSIZE * sizeof(weights);
> weights huge *accumulator =  (weight *)farmalloc(MEMSIZE);

Mike writes of problems accessing accumulator[].  The problem here is
that both sizeof() and DBSIZE are int's, so the calculation of memsize
is done as int, then assigned to memsize.  The fix is to either cast
something to long before multiply, or change DBSIZE to long.  TC++
*will* allocate >64k blocks with farmalloc().  Be sure to check against
NULL, and don't expect to be able to run programs allocating large
amounts of memory under the IDE.

The 64k limit of Turbo C++ exists only with memory allocated with 'new'
or malloc().  Although >64k statics require explicit declaration, IMHO
this isn't much of a problem.  The 'new' limit, however, is highly
annoying.
  
Quimby
 
(mailer disfunctional, replies to: quimby@mts.rpi.edu,
                                   quimby@rpitsmts.bitnet)
 
NOTE:  Although statics >64k seem to allocate correctly, they still
generate 'stack overflow' messages at run time if TC++'s stack
checking is enabled.  At this point I'm not certain if it's a problem
with my code, the allocation, or the stack checking.