Re: while( *it == value && it != v.end() )

[mathieu]

On Feb 13, 10:07 pm, Paul Pluzhnikov <ppluzhnikov-...@charter.net>
wrote:
> "mathieu" <mathieu.malate...@gmail.com> writes:
> >   Just to be sure I am double-checking here.
> >   Is there a way to make gcc produce a warning when a code is
> > dereferencing an end iterator ? Or does this involve too much static
> > analysis ?
>
> The latter.
> You can however ask newer versions of g++ to catch this at runtime:
>
> $ cat junk.cc
> #include <vector>
>
> typedef std::vector<int> VI;
>
> int main()
> {
>     VI v(10);
>     VI::iterator it = v.begin();
>     while (*it == 0 && it != v.end()) ++it;
>     return 0;
>
> }
>
> $ /usr/local/gcc-3.4.6/bin/g++ -g junk.cc && ./a.out && echo ok
> ok
> $ /usr/local/gcc-3.4.6/bin/g++ -g junk.cc -D_GLIBCXX_DEBUG && ./a.out
> /usr/local/gcc-3.4.6/bin/../lib/gcc/i686-pc-linux-gnu/3.4.6/../../../../include/c++/3.4.6/debug/safe_iterator.h178:
>     error: attempt to dereference a past-the-end iterator.
>
> Objects involved in the operation:
> iterator "this" @ 0x0xbfffdc60 {
> type = 
> N11__gnu_debug14_Safe_iteratorIN9__gnu_cxx17__normal_iteratorIPiN10__gnu_norm6vectorIiSaIiEEEEEN15__gnu_debug_def6vectorIiS6_EEEE
>  (mutable iterator);
>   state = past-the-end;
>   references sequence with type `N15__gnu_debug_def6vectorIiSaIiEEE' @ 
> 0x0xbfffdc60}
>
> Aborted (core dumped)

sweet !

Thanks,
-M