Topic: About set...


Author: jpotter@falcon.lhup.edu (John Potter)
Date: Mon, 30 Apr 2001 02:39:26 GMT
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On Sun, 29 Apr 2001 13:20:42 GMT, "Igor Krasnopeev"
<captaincomatoz@mail.ru> wrote:

> Total order is not maintained!
>
> Any suggestions?

See lwg issue 103.

John

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Author: "Igor Krasnopeev" <captaincomatoz@mail.ru>
Date: Sun, 29 Apr 2001 13:20:42 GMT
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>From Standard C++ Library: Class Reference we have:

set<Key, Compare, Allocator> is an associative container that supports
unique keys and allows for fast retrieval of the keys. A set contains, at
most, one of any key value. The keys are sorted using Compare.

Since a set maintains a total order on its elements, you cannot alter the
key values directly. Instead, you must insert new elements with an
insert_iterator.

But, also:

Iterators

iterator begin();

Returns an iterator that points to the first element in self.

So, it is possible to wtire next code:

std::set<int> S;
S.insert(1);
S.insert(2);

std::copy(S.begin(), S.end(), ostream_iterator<int,char>(std::cout," "));
/ / output is 1 2

std::set<int> SI = S.begin();
*SI = 3;

std::copy(S.begin(), S.end(), ostream_iterator<int,char>(std::cout," "));
/ / now output is 3 2

Total order is not maintained!

Any suggestions?

Igor Krasnopeev


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