Re: Is pushing into reserved space invalidating iterators?
You understood wrong. About vector::insert(), the standard states
explicitly in 23.2.4.3: "Causes reallocation if the new size is greater
than the old capacity. If no reallocation happens, all the iterators and
references before the insertion point remain valid." In this case end()
is *after* the insertion point, so it gets invalidated.
I guess that I missed the point of the insertion point.
Thanks for clarifying that my code resulted in undefined behaviour.
If you had asked
about begin() then the answer would have been different: it won't be
invalidated because it's before the insertion point.
This is most puzzling to me since x.begin() == x.end(),
how can it be both before and after an insertion point?
so I ran the following:
===================
int main(int argc, char** argv)
{
std::vector<int> x;
x.reserve(1);
std::vector<int>::iterator i = x.begin();
x.push_back(1);
if (i != x.end())
return *i;
}
===================
result: again an assertion failed on the compare.
I conclude that both begin() and end() of an empty vector
return an iterator AT the insertion point of a subsequent push_back,
which is neither before nor after that point. Since AT is
not before, vc's stl implementors were allowed to let
a debug assertion fail and they won't get a bug report
from me, at least not for this one.
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