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c++seterase

C++: Deleted element still in set after calling Erase

I got a code like this:

for (set<GROUP*>::iterator i = Data.m_Resulting.begin(); i != Data.m_Resulting.end();)
{
    printf("Deleting %d\n", (*i)->nId);
    Data.m_MpptPool.erase(i++);
}

printf("Remains in pool: %d\n", Data.m_MpptPool.size());

// Dump Pool:

for (set<GROUP*>::iterator i = Data.m_MpptPool.begin(); i != Data.m_MpptPool.end(); i++)
{
    printf("\t %d\n", (*i)->nId);
}

If before deleting there was 2 objects in the set , and the firs loop deletes one of them the .size() function shows a correct number (1) However, the second for-loop that prints the contents of my set shows both elements in there. Later, referring to this element causes segmentation fault. What can be the problem here?

Solution

  • You can not use an iterator from one std::set (m_Resulting) on another std::set (m_MpptPool). This is undefined behaviour, you need to use the value:

    Data.m_MpptPool.erase(*it++);