Re: iterator error

From:

"James Kanze" <james.kanze@gmail.com>

Newsgroups:

comp.lang.c++

Date:

6 Apr 2007 02:19:00 -0700

Message-ID:

<1175851140.818746.225130@o5g2000hsb.googlegroups.com>

On Apr 6, 3:02 am, "Victor Bazarov" <v.Abaza...@comAcast.net> wrote:

=C0=D6=C0=D6=B4=F3=CC=EC=CA=A6 wrote:

windows xp, visual studio 2005
-----------------------------------------------------------------------=

-----------------------------------------------------------

#include <iostream>
#include <map>
using namespace std;

int main()
{
map<int, int>::iterator it = 0;
if( it != 0 ) //break point,
this is an run time error?
cout<<"ok!";
}
-----------------------------------------------------------------------=

-----------------------------------------------------------

why it can be assign "0", but can't compare with "0"?

The iterator type in 'map' is implementation-defined. What
it means to initialise it with (int)0 is implementation-defined.
Why operator != (int)0 doesn't work is (you guessed it!)
implementation-defined.

It's not even implementation-defined, it's undefined.

Most good implementations will not compile either of the above
lines.

You need to either look at the code
in the debugger to see what's going on or ask in the newsgroup
dedicated to your implementation (microsoft.public.vc.* family
of newsgroups come to mind).

Actually, he needs to change his code. It might help if he
explained what he is trying to accomplish.

--
James Kanze (Gabi Software) email: james.kanze@gmail.com
Conseils en informatique orient=E9e objet/
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