Question

Check this code:

#include "stdafx.h"
#include <list>

int _tmain(int argc, _TCHAR* argv[])
{
    std::list<int> mylist;
    mylist.push_back(1);
    std::list<int>::iterator i = mylist.end();
    if( i == mylist.end() )
        printf( "end is end\n" );

    mylist.clear();
    if( i == mylist.end() )
        printf( "never get here because Microsoft seems to "
                "think the iterator is no longer safe.\n" );

    return 0;
}

Now, according to cplusplus.com this shouldn’t be a problem, and in release mode, I think this is fine and doesn’t cause any issues really, but debugging becomes impossible as this just bails without letting me continue. Any pointers?

Answer 1

Other answers point out that, in general, you can’t rely on a container’s past-the-end iterator remaining valid when the container is cleared. However, the past-the-end iterator of a list should indeed remain valid:

C++11 23.3.5.4/3 Effects: Invalidates only the iterators and references to the erased elements.

The past-the-end iterator does not refer to any element, so should not be invalidated.