I've looked up in the standard and equality comparison between
iterators
associated to different containers seems not to be banned, i.e. looks
like
the following is legal C++:

 #include <set>

 int main()
 {
   std::set<int> s1,s2;
   std::set<int>::iterator it1=s1.begin(),it2=s2.begin();
   it1==it2;
 }

However, "safe mode" frameworks like for instance that of Visual
Studio
assert on the program above, and in general I think there's a general
opinion that you can only compare iterators from the same container.

Anyone can point to the relevant sections of the standard, if any,
clarifying this issue?

Thank you,

Joaqu   n M L   pez Mu   oz
Telef   nica, Investigaci   n y Desarrollo


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On Dec 17, 5:13 pm, Joaqu   n M L   pez Mu   oz <joaq...@tid.es> wrote:
> I've looked up in the standard and equality comparison between
> iterators
> associated to different containers seems not to be banned, i.e. looks
> like
> the following is legal C++:
>
>  #include <set>
>
>  int main()
>  {
>    std::set<int> s1,s2;
>    std::set<int>::iterator it1=s1.begin(),it2=s2.begin();
>    it1==it2;
>  }
>
> However, "safe mode" frameworks like for instance that of Visual
> Studio
> assert on the program above, and in general I think there's a general
> opinion that you can only compare iterators from the same container.
>
> Anyone can point to the relevant sections of the standard, if any,
> clarifying this issue?

There is an active issue (#446) for this, see:
http://www.open-std.org/jtc1/sc22/wg21/docs/lwg-active.html#446

Stefanus


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