<ee****@gmail.com> schrieb im Newsbeitrag
news:11**********************@z14g2000cwz.googlegr oups.com...
Hello,
I am facing a starnge problem while erasing the last member in a
vector. I am using VC++ .NET 2002 complier. I have vector of
CComPtr<..> (irrelevant here),
Perhaps it is irrelevant for your problem, but you should not put instances
of CComPtr into C++ containers. Some of these containers (or some
implementations of them) do not work well with objects overloading
operator&.
and then I iterate over the vector. If
it is the iterator, then I remove the element from the vector using
vecObjects.erase(it).
When you iterate through a container and try to erase its last element, make
sure not to increment the iterator after erasing. Actually you should never
increment an iterator after erasing the element it refers to. For all
containers, all iterators refering to the erased element become invalid. So
don't do something like this
for (SomeContainer::iterator it = myContainer.begin(); it !=
myContainer.end(); ++it)
{
if (RemoveThisElement(*it)) myContainer.erase(it);
}
If SomeContainer is an std::vector, this seems to work until you try to
erase the last element, but actually it will not examine those elements
imediately following an element, that will be removed. Now if you erase the
last element, end() will change (in some implementations end() will become
equal to the iterator for the erased elemet) and due to the final increment
the test for equality to end() will fail and the loop will continue until it
reaches the end of allocated memory. (Or it will behave entirely different,
after all that's the problem with undefined behaviour.)
HTH
Heinz