[cs13001] Question after class

[Mikhail Nesterenko]

> There was a question after class about modifying a container in a
> loop without breaking things with the iterator. I had mentioned my
> solution in Java and you wanted to look up what the standard was for
> C++.


In general, modifying a container invalidates iterators. However,
operations that invalidate iterators often return "convenient"
iterators. For example, erase() returns the iterator to the next
element (in the updated container) after the one erased. Hence the
idiom:

for(vector<int>::iterator it=myVector.begin(); 
    it != myVector.end(); 
    /* no increment here */)
    if(must_erase)
        it = myVector.erase(it);
    else
        ++it;