CodeGuru Home VC++ / MFC / C++ .NET / C# Visual Basic VB Forums Developer.com
Results 1 to 3 of 3
  1. #1
    Join Date
    Feb 2010

    Are std::list iterators broken in VC++2008?

    From my understanding of STL, list iterators are supposed to remain valid after a splice operation, however I seem to be getting a problem when I use an iterator to splice one object from list A to list B. The iterator seems to have been invalidated by the STL implementation. If I then try to use the same iterator to splice the object back from list B to list A, "bad things" happen (assertion fail on a debug build, worse on a release build). Here is a simple test case:

    #include <list>
    #include <assert.h>

    typedef std::list<int> IntList;

    extern "C" int main(int argc, char *argv[])
    IntList list1, list2;

    IntList::iterator iter = list1.insert(list1.end(), 42);
    list2.splice(list2.end(), list1, iter);
    list1.splice(list1.end(), list2, iter);
    assert(list1.size() == 1);
    assert(*(list1.begin()) == 42);

    return 0;

    This code builds and appears to run fine using GCC, but not with Visual Studio 2008 (the second splice operation fails an internal assertion). Am I missing something fundamental here or is this a problem with VC++?


  2. #2
    Join Date
    Aug 2000
    West Virginia

    Re: Are std::list iterators broken in VC++2008?

    I am not sure, but I think the result of the second splice operation
    is undefined. According to the standard, the splice operation:

    Invalidates only the iterators and references to the spliced element
    So, I read that to mean that the first splice operation would invalidate
    the iterator (iter) , which you use in the second splice operation.

    I could be wrong ... I am not a language expert on these types
    of matters.

  3. #3
    Join Date
    Feb 2010

    Re: Are std::list iterators broken in VC++2008?

    I suspect you are correct, at least from what I can tell tracing through VC++'s STL list source. The problem is relatively easily fixed/worked around by reassigning the iterator to list2.end() and decrementing it after the first splice, but one line of code is usually preferable to three

Tags for this Thread

Posting Permissions

  • You may not post new threads
  • You may not post replies
  • You may not post attachments
  • You may not edit your posts

Windows Mobile Development Center

Click Here to Expand Forum to Full Width

On-Demand Webinars (sponsored)

We have made updates to our Privacy Policy to reflect the implementation of the General Data Protection Regulation.