comp.lang.c++.moderated Google Group

Re: Array vs Vector performance

krisp...@yahoo.co.uk — Thu, 24 Jul 2008 01:58:15 UT

It indeed turned out to be an issue of _SECURE_SCL. (The tests I did
have all been with release builds).
Strangely now the vector version outperforms array. This is because
the compiler generated assembly shows loop unwinding on vector
iteration, but surprisingly not the array one.

Re: Array vs Vector performance

joshuamaur...@gmail.com — Thu, 24 Jul 2008 01:40:18 UT

First do as Mathias Gaunard says.
Even then, as Hak...@gmail.com pointed out, your test is comparing
apples to oranges. std::vector stores its elements on the heap. Your
array is statically allocated on the stack. The vector test is getting
the heap memory management overhead, a.k.a. new[] and delete[] calls.

Re: Fat String Class

albertobarb...@libero.it (Alberto Ganesh Barbati) — Thu, 24 Jul 2008 01:40:24 UT

Le Chaud Lapin ha scritto:
I guess "language" is a more appropriate term than locale here, unless
with "locale" you mean other kind of contextual metadata, which is bound
to be more complex.
Ok, so... what about this:
"Let's eat spaghetti, a bratwurst and a crème brûlée"
is this English, Italian, German or French? You can't simply attach

Re: Fat String Class

b...@gmb.dk (Bo Persson) — Thu, 24 Jul 2008 01:40:22 UT

You will have to store a lot of external state to determine that
English "mine" can also mean "Mine" (noun) in German, or "verminen"
(verb) if it blows up. It can also mean "Grube", or "Mine"(!) if you
dig in the ground.
The still other English "mine", like in "belongs to me" needs even
more context.

Re: Order of destruct of local variables

joshuamaur...@gmail.com — Thu, 24 Jul 2008 01:36:23 UT

Actually, no. This reasoning does not hold in all cases. I just had a
rather long argument with a Java friend of mine over whether this
should always be the case. It is in Java. C++ is more lax than your a
priori reasoning would show. For example, the following program has
unspecified, but not undefined, behavior:

Re: "Function Types"

t...@math.tu-berlin.de (Thomas Richter) — Thu, 24 Jul 2008 01:37:08 UT

In fact, the two types are precisely identical. A function type is
always a pointer to a function.
The second invoke is actually doing something different.It doesn't take
a function pointer argument, but a pointer to a function pointer
argument, i.e. two indirections instead of one. There is no "no
indirection" version of function types, though you may simply strip the

Re: Array vs Vector performance

poen...@htwm.de (Andre Poenitz) — Thu, 24 Jul 2008 01:30:22 UT

Out of curiosity: Could you show the three versions of assembly code
- or if this is deemed too much Off Topic - sent them as private mail?
I'd really like to see what halves the time over a "straightforward"
assembly.
{ As used to clarify or discuss C++ implementation issues assembly code would
not be off-topic. -mod }

Re: Implementing call back functions effeciantly

aman....@gmail.com — Thu, 24 Jul 2008 01:23:13 UT

You might find the Command design pattern implemented using
polymorphic function-objects to be quite useful. It's the object-
oriented implementation of callbacks & is usually neater than the
function pointer implementation.
regards,
Aman Angrish.

Re: Available C++ Libraries FAQ

marlow.and...@googlemail.com — Thu, 24 Jul 2008 01:24:10 UT

I have sent several updates to Nikki, some of which he has already
incorporated. So hopefully several more of the links should work now.
Regards,
Andrew Marlow

Singletons and destructors

all...@tele.ntnu.no (Rune Allnor) — Thu, 24 Jul 2008 01:23:20 UT

Hi all.
I have struggled for a couple of days with a singleton pattern.
It turned out that the cause of the problem is that the destructor
of a singleton pattern is not called unless somebody calls a
'delete' to a pointer to the singleton.
Below is an example, where the program reports what methods
it calls. The only way I can find to see a report from the

Re: RValue Arrays

i...@unicals.com (Ivan A. Kosarev) — Thu, 24 Jul 2008 01:23:21 UT

Well, the lvalueness is a property of expressions, not objects
themselves, so that wouldn't be correct to say that elements of an array
are lvalues or rvalues.
Then, that's hardly an example of inheriting of a problem from C89 as
there are very different models in C and C++ in this regard: in C89
rvalues are never objects while in C++ class rvalues always are. (Note

Array of unknown bound

rkld...@gmail.com — Thu, 24 Jul 2008 01:23:50 UT

Hi,
$8.3.5 para 6 says "-6- If the type of a parameter includes a type of
the form ``pointer to array of unknown bound of T'' or ``reference to
array of unknown bound of T,'' the program is ill-formed.*
[Footnote: This excludes parameters of type ``ptr-arr-seq T2'' where
T2 is ``pointer to array of unknown bound of T'' and where ptr-arr-seq

Re: = delete - what does this do?

francis.glassbo...@btinternet.com (Francis Glassborow) — Thu, 24 Jul 2008 01:23:35 UT

small nit, it is 'delete' not 'deleted' (that would be a new keyword)

Re: ios_base::app Standard behavior

albertobarb...@libero.it (Alberto Ganesh Barbati) — Thu, 24 Jul 2008 01:19:20 UT

francois.cppd...@free.fr ha scritto:
According to the C standard, the effect of the "a" flag is "all write to
the file are forced to the current end-of-file, regardless of
intervening calls to the fseek function." In particular, it does not
require nor imply that the initial position of the stream should be set

Re: RValue Arrays

i...@unicals.com (Ivan A. Kosarev) — Wed, 23 Jul 2008 13:28:14 UT

Both the initializations try to bound to a temporary and thus forbidden.
GCC complains about that pretty clearly. What compiler you use?
Yes, they do.