Re: Is pushing into reserved space invalidating iterators?

From:

Jiri Palecek <jpalecek@web.de>

Newsgroups:

comp.lang.c++.moderated

Date:

Wed, 5 Mar 2008 16:31:34 CST

Message-ID:

<fqn3dh$6e8$1@ns.felk.cvut.cz>

MathGis wrote:

Is the following code legal?
I'm asking since the iterator debugging facility of VC++2005's stl
gives an assertion failed at runtime.

#include <vector>

int main(int argc, char** argv)
{
     std::vector<int> x;
     x.reserve(1);
     std::vector<int>::iterator i = x.end();
     x.push_back(1); // No reallocation
     if ( i != x.end()) // Debug Assertion failed: iterators
incompatible?

I don't know exactly what "iterators incompatible" means, but yes, the
iterator is invalidated here.

return *i; // Debug Assertion failed: vector iterator not
dereferencable?
}

I had understood that iterators only become invalid when vector
operations cause reallocation.

That is only part of the truth: Iterators become invalid when an operation
causes reallocation, or when you insert or delete elements that are before
them.

Regards
     Jiri Palecek

--
      [ See http://www.gotw.ca/resources/clcm.htm for info about ]
      [ comp.lang.c++.moderated. First time posters: Do this! ]