comp.lang.c++ Google Group

Re: How is map, int> stored? (for graph algorithms)

2009-11-08T21:35:44Z

By "hash", I meant to ask how are the keys compared? For a
map<vector<int>, int>, how would the keys be compared? I assume the
comparer must walk down both vectors and do element-wise comparison,
and if two vectors are the same through N elements but one vector
is longer, then the shorter one wins the comparison?

Re: Accessing private members...

2009-11-08T21:19:47Z

What he is saying is that the line c = a.p(); calls function p of the
object a, and sets c to the result of this. The calling of function p
has nothing to do with c, c is just where the result will go once
you've got it, so you can't control the access to p by this means.
But in the example you have given, member functions of b can access

Re: How is map, int> stored? (for graph algorithms)

2009-11-08T21:11:59Z

On Nov 8, 10:19 am, "AnonMail2...@gmail.com" <anonmail2...@gmail.com>
wrote:
Well, C++03 the term hash does not apply. For TR2 or C++0x, we're
getting hash sets and hash maps, so it does apply in these cases.
However, the OP is still wrong as he implied that std::map is a hash
map. It is not. It is a red-black binary tree (or at least almost

Re: serialization

2009-11-08T21:09:18Z

At the very least, IMAO, C++ should have reflection, but only at
compile time. Possibly / preferably through some template-like
facilities. Being able to iterate over members of a class at compile
time in a generic way would impose no additional costs, contrary to
the oft reason cited reason of "pay only for what you use".

Re: RNGs: A Super KISS

2009-11-08T18:59:58Z

"io_x" <a...@b.c.invalid> ha scritto nel messaggio
not define, better declare

Re: How is map, int> stored? (for graph algorithms)

2009-11-08T18:19:19Z

std::map uses the operator<() (less than) function to order it's
elements. The term hash does not apply. std::pair defines this as:
template<class Ty1, class Ty2>
bool operator<(const pair<Ty1, Ty2>& left, const pair<Ty1, Ty2>&
right)
{
return left.first < right.first || !(right.first < left.first) &&

Re: How is map, int> stored? (for graph algorithms)

2009-11-08T17:55:51Z

How does STL hash pair<int, int> for use as a map key?

Re: Binary file IO: Converting imported sequences of chars to desired type

2009-11-08T17:11:23Z

I'm getting tired with re-iterating this for people who
are not interested in actually evaluating the numbers.
Look for an upcomimg post on comp.lang.c++.moderated, where
I distill the problem statement a bit, as well as present
a C++ test to see what kind of timing ratios I am talking about.
Rune

Re: c++0x pods and constructors

2009-11-08T14:33:34Z

Or that there are two different C compilers on the system, and
they use different ABI's. Here, too, the case should be fairly
rare, due to the fact that most OS's today define their
interface in terms of C.
It would almost certainly break something.
Yes. And for various reasons, I've not been able to study much

Re: Accessing private members...

2009-11-08T14:29:44Z

I'm not entirely sure what you mean. I would like the access to the members
to be selective. Some objects can see some members while other objects
(particularly the ones of the same class) can see others. The member p()
above is private and hence the second line should cause a compiler error.
Yes, adding a wrapper would be one solution.

Re: Binary file IO: Converting imported sequences of chars to desired type

2009-11-08T14:27:41Z

Which, of course, raises the question as to why. They're not
very useful unless you're doing exceptionally low level work.
The original comment was just that---a parenthetical comment.
Text formats have many advantages, WHEN you can use them. It's
also obvious that they have additional overhead---not nearly as

Ralph Lauren polo

2009-11-08T12:41:55Z

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Wonders of Allah in Dolphins

2009-11-08T11:03:36Z

Wonders of Allah in Dolphins
For dolphins, breathing is not a reflex, as it is for humans and other
land mammals, but rather a voluntary movement. In other words,
dolphins decide to breathe like we decide to walk. There is also a
precaution taken in order to prevent the animal's being drowned while
sleeping in water. While sleeping, the dolphin uses the right and left

Re: How is map, int> stored? (for graph algorithms)

2009-11-08T07:51:17Z

Digital Puer wrote, On 8.11.2009 6:34:
Using std::vector<> as a key for two integere elements is very suboptimal.
There is extra indirection, which means its copy ctor and other operations
have lots more overhead than that of std::pair<>. Also,
sizeof(std::vector<int>) > sizeof(std::pair<int,int>). The access to the

Re: Structure definitions

2009-11-08T05:58:47Z

Hi
Because it is a homework, I should give you just few hints:
1. Use const types rather than macros:
const int STUDENTS = 100;
2. The name of your array and one of its struct members are same:
score. use different names.
3. You can intialize the first 5 array elements using array
initilizers list
almost in the same way as initializing array of integers: