RE: [Dev-C++] dynamic allocation and structs

[Per W. <pw...@ia...>]

Exactly why my previous mail specified use-cases.

- Sparse matrix, where a lot of entries are NULL.
- Quick sort, since it's enough to move the pointers.
- Different object types for each index, simulating C++ abstract base
class.
- Supports large vector in 16-bit code, where it's possible to have 16000
entries of up to 64000 byte size each.

/Per W

On Fri, 25 Oct 2002, Ioannis Vranos wrote:

> > -----Original Message-----
> > From: Ioannis Vranos [mailto:no...@ho...] 
> > Sent: Friday, October 25, 2002 12:39 PM
> > To: Dev-C++ Mailing List (dev...@li...)
> > Subject: RE: [Dev-C++] dynamic allocation and structs
> > 
> > 
> > > -----Original Message-----
> > > From: Per Westermark [mailto:pw...@ia...] 
> > > Sent: Friday, October 25, 2002 11:51 AM
> > > To: Ioannis Vranos
> > > Cc: 'Dev-C++ Mailing List'
> > > Subject: RE: [Dev-C++] dynamic allocation and structs
> > > 
> > > 
> > > The trick is that vector isn't programming. It is a standard 
> > > - and very
> > > old - mathematical term for a one-dimensional matrix.
> > 
> > 
> > Yes, but when we speak of C++ code, calling a built in array 
> > a "vector" can only be confusing.
> > 
> > 
> > 
> > > There has been
> > > millions of vector implementations before STL did a template 
> > > version, and
> > > the probability of a finding a STL construct in a C program 
> > > is not that
> > > high :-)
> > 
> > 
> > Yes, but it still can be confusing to C++ programmers.
> > 
> > 
> > 
> > > 
> > > While code might syntactically switch around between
> > > (*a).x,
> > > a->x
> > > a[0].x
> > > 
> > > the third form is definitely dangerous to use when a is only 
> > > a pointer to
> > > a single element. If there is an element zero, the logical 
> > > conclusion is
> > > that there must be a element one.
> > 
> > 
> > Yes, if there is only one element i would use the -> only. 
> > When we have more the [] is more suitable. Both are valid.
> 
> Also i cannot understand why someone would create a single dimensional
> array of pointers on the free store and then assign an element on the
> free store to each of them. It's a total waste of everything. :) Using a
> simple pointer and allocating space for the elements directly on the
> free store would be a reasonable thing to do.
> 
> /* Array of 100 mystructs on the free store */
> struct mystruct *p=malloc(100*sizeof(*p));
> 
> 
> 
> Ioannis
> 
> * Ioannis Vranos
> * Programming pages: http://www.noicys.freeurl.com
> * Alternative URL: http://run.to/noicys
> 
> 
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