Re: Using list.splice unable to dereference iterator
Doug Harrison [MVP] wrote:
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.
The code is wrong, or perhaps he is just a bit early?
The C++0x draft specifically says that it2 will remain valid, and
refer to the same element, but iterate into the other list after the
splice.
Bo Persson
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