Re: Using list.splice unable to dereference iterator

From:
"Doug Harrison [MVP]" <dsh@mvps.org>
Newsgroups:
microsoft.public.vc.stl
Date:
Tue, 03 Mar 2009 10:39:58 -0600
Message-ID:
<36nqq49rgggf2q2sqsg9ik90jl3imae6g9@4ax.com>
On Tue, 3 Mar 2009 06:04:15 -0800, Finn M?ller Hansen
<FinnMllerHansen@discussions.microsoft.com> wrote:

Why can't I dereference the iterator - any good ideees. It worked in 2003
version.

#include "stdafx.h"

#include <list>

using namespace std;

class A
{
    int m_Member1;
};

int _tmain(int argc, _TCHAR* argv[])
{
    list<A*> l1;
    list<A*> l2;

    for (int i = 0; i < 10; i ++)
    {
        A * pA = new A();
        l1.insert(l1.end(), pA);
    }

    for (int i = 0; i < 10; i ++)
    {
        A * pA = new A();
        l2.insert(l2.end(), pA);
    }

    list<A*>::iterator it1 = l1.begin();
    list<A*>::iterator it2 = l2.begin();

    it1 ++;
    it2 ++;

    // This is OK

    A * pX = *it2;

    l1.splice(it1, l2, it2);

    // This next statement gives the result "list iterator not dereferencable"
in VS 2008 (worked in previous versions)

    A * pY = *it2;

    return 0;
}


Splicing invalidates iterators and references to the spliced element, so
it2 is invalidated, and your code is wrong. The iterator it1 remains valid,
though.

--
Doug Harrison
Visual C++ MVP

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