On the book <Generic Programming and the STL>( Matthew . H . Austern ),this function is defined as
iterator set::begin() const.
However, why should a const object returns a non-const iterator?
Then, I found, in this book, the semantic of set::iterator is defined as same as set::const_iter ator. Both of them must be const!
I tried to read the source of GNU STL(version 3.4.1).They were using a red-black tree to implant it (std::set has a _RBtree.) .Both set::iterator and set::const_iter ator are simply defined as _RBtree::const_ iterator.
But, in VC++, it is deferent.
There is a base class named xtree which also a red-black tree. Then the class map and set inherit from xtree (which implantation is better? is-a? has-a?).They don't defined iterator and const_iterator theirself,just inherit them from the base class xtree,and the member function begin() is defined as :
const_iterator set::begin() const;
iterator set::begin().
So ,we can initialize a mutable set, get the begin of it, then try to modify it!
The following code has been compiled successful under VC++2003
int a[4]={1,2,3,4};
std::set<int> s(a,a+4);
std::set<int>:: iterator i=s.begin();
(*i) = 9;
std::cout<<"Now s = ";
std::copy(s.beg in(),s.end(),st d::ostream_iter ator<int>(std:: cout,","));
std::cout<<std: :endl;
std::set<int>:: const_iterator p=s.find(9);
if(p != s.end() )
std::cout<<(*p) ;
else std::cout<<"Can not find the element special"<<std:: endl;
A set must be a sorted container, but now it is not! So anything terrible things it would happen.
Is this a bug of VC++?
A bug of VC++.net STL
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Jul 22 '05
11 3256
Have you got the rigth answer??
I've been thinking about it since we last meet. This thread has been closed and replies have been disabled. Please start a new discussion. Similar topics |
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