Re: Problem with pointers and iterators

[Pete Becker]

On 2008-10-06 16:56:31 -0400, Griff Johns <[e-mail]:

>
MyObjectList::iterator it;
for (it = list.begin(); it != list.end(); ++it) {
// I used to be able to do this:
MyObject* p_obj = it;
Foo(p_obj);

// Or this
Foo(it);

}

But now the error I get is 'cannot convert parameter 1 from
'std::vector<_Ty>::iterator' to 'MyObject *'

Write on the blackboard 100 times: "An iterator is not a pointer."

In VC6 this worked because vector::iterator was a typedef for T*. In
later versions that changed. Both forms satisfy the requirements of the
standard.

Well, you have an iterator that refers to an object, and you need the
address of that object. So there are two steps: get a reference from
the iterator, and take its address.

--
Pete
Roundhouse Consulting, Ltd. (www.versatilecoding.com) Author of "The
Standard C++ Library Extensions: a Tutorial and Reference
(www.petebecker.com/tr1book)

[Richard Tobin]

In article <2008100617014316807-pete@versatilecodingcom>,
Pete Becker <pe**@versatilecoding.comwrote:
[deleted]

For those baffled by this slew of messages, the original seems to have
been posted to comp.lang.c++ with followups set to comp.lang.c.
I'm posting this to both with followups set to comp.lang.c++ so
that it can be taken up over there.

-- Richard
--
Please remember to mention me / in tapes you leave behind.

[Eric Sosman]

Pete Becker wrote:

On 2008-10-06 16:56:31 -0400, Griff Johns <[e-mail]:

>>
MyObjectList::iterator it;
[...]

Write on the blackboard 100 times: "An iterator is not a pointer."
[...]

Write on the blackboard 100 times: "C++ is not C," and then
consider using comp.lang.c++ for C++ discussions.

--
Er*********@sun.com

[CBFalconer]

Eric Sosman wrote:

Pete Becker wrote:

>Griff Johns <[e-mail]:

>>MyObjectList::iterator it;
[...]

Write on the blackboard 100 times: "An iterator is not a pointer."
[...]

Write on the blackboard 100 times: "C++ is not C," and then
consider using comp.lang.c++ for C++ discussions.

At last, a sane answer for c.l.c.

--
[mail]: Chuck F (cbfalconer at maineline dot net)
[page]: <http://cbfalconer.home.att.net>
Try the download section.

[Richard Bos]

CBFalconer <cb********@yahoo.comwrote:

Eric Sosman wrote:

Pete Becker wrote:

Griff Johns <[e-mail]:

MyObjectList::iterator it;
[...]

Write on the blackboard 100 times: "An iterator is not a pointer."
[...]

Write on the blackboard 100 times: "C++ is not C," and then
consider using comp.lang.c++ for C++ discussions.

At last, a sane answer for c.l.c.

For Nybbas' sake, Chuck, you don't _have_ to turn yourself into a
Looking-Glass Kenny!

Richard