Re: boost alternative to realloc

From:
"Leigh Johnston" <leigh@i42.co.uk>
Newsgroups:
comp.lang.c++
Date:
Sat, 17 Apr 2010 20:05:30 +0100
Message-ID:
<OOidnV39WYTpm1fWnZ2dnUVZ8s2dnZ2d@giganews.com>
"Kai-Uwe Bux" <jkherciueh@gmx.net> wrote in message
news:hqd0h7$tos$1@news.doubleSlash.org...

Leigh Johnston wrote:

"Alf P. Steinbach" <alfps@start.no> wrote in message
news:hqcu3t$7lo$1@news.eternal-september.org...
<snip>

Unless I am mistaken you are basically advocating that the following code
is correct according to the standard:

void foo()
{
  std::vector<int> v;
  v.reserve(2);
  v.push_back(41);
  *(&v[0]+1) = 42;
}

The above code is plain wrong.


Please define your terms: what do you take "correct" to mean, and what is
"plain wrong"? Does the code have UB according to the standard?

If I you disagree then your position is
untenable. Anyone with an once of common sense would use std::vector in
the ways it was designed for and not abuse it like you are suggesting.


Keep the context in mind: Alf was pondering this option in the context of
the OP's request: If the alternative is to use malloc(), free(), and
realloc() manually, why not use the above? Or, why not do something like
the
above inside the implementation of a little wrapper that, to the outside,
looks like the wrapper for malloc(), free(), and realloc() that the OP was
looking for?

Best

Kai-Uwe Bux


It is wrong in the sense that it is bad practice irrespective of whether it
is UB or not. std::vector is a container, it is not a general purpose
memory allocator. The correct solution is to write a class designed for the
specific requirements the OP had and I am glad to say that the OP had
sufficient common sense to realize this straight away, common sense that Alf
seems to lack.

/Leigh

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