I need some help guys - I'm writing a little program for cs... and my problem is as follows:

I've got two classes, edge and Node. In class node, I've got a list:

list<edge> edges;

In a function of this class, I'm getting a reference to a priority queue of type:

priority_queue<Edge> &neighbours

What I want to do now, is insert some of the items of the list in the priority queue.
I've created an iterator, which I later correctly initialize:

list<Edge>::iterator position;

Now, I'm trying to insert the the data from the iterator in the priority queue:

neighbours.push(*position);

This does not work - the compiler errors I get are as follows:

/usr/lib/gcc/x86_64-pc-linux-gnu/3.4.0/include/g++-v3/bits/vector.tcc: In member function `Edge& Edge::operator=(const Edge&)':
/usr/lib/gcc/x86_64-pc-linux-gnu/3.4.0/include/g++-v3/bits/vector.tcc:238: instantiated from `void std::vector<_Tp, _Alloc>::_M_insert_aux(__gnu_cxx::__normal_iterator<_Tp*, std::vector<_Tp, _Alloc> >, const _Tp&) [with _Tp = Edge, _Alloc = std::allocator<Edge>]'
/usr/lib/gcc/x86_64-pc-linux-gnu/3.4.0/include/g++-v3/bits/stl_vector.h:564: instantiated from `void std::vector<_Tp, _Alloc>::push_back(const _Tp&) [with _Tp = Edge, _Alloc = std::allocator<Edge>]'
/usr/lib/gcc/x86_64-pc-linux-gnu/3.4.0/include/g++-v3/bits/stl_queue.h:431: instantiated from `void std::priority_queue<_Tp, _Sequence, _Compare>::push(const typename _Sequence::value_type&) [with _Tp = Edge, _Sequence = std::vector<Edge, std::allocator<Edge> >, _Compare = std::less<Edge>]'
Node.cc:33: instantiated from here
/usr/lib/gcc/x86_64-pc-linux-gnu/3.4.0/include/g++-v3/bits/vector.tcc:238: error: non-static reference member `Node&Edge::target', can't use default assignment operator
/usr/lib/gcc/x86_64-pc-linux-gnu/3.4.0/include/g++-v3/bits/stl_function.h: In member function `bool std::less<_Tp>::operator()(const _Tp&, const _Tp&) const [with _Tp = Edge]':
/usr/lib/gcc/x86_64-pc-linux-gnu/3.4.0/include/g++-v3/bits/stl_heap.h:166: instantiated from `void std::__push_heap(_RandomAccessIterator, _Distance, _Distance, _Tp, _Compare) [with _RandomAccessIterator = __gnu_cxx::__normal_iterator<Edge*, std::vector<Edge, std::allocator<Edge> > >, _Distance = long int, _Tp = Edge, _Compare = std::less<Edge>]'
/usr/lib/gcc/x86_64-pc-linux-gnu/3.4.0/include/g++-v3/bits/stl_heap.h:203: instantiated from `void std::push_heap(_RandomAccessIterator, _RandomAccessIterator, _Compare) [with _RandomAccessIterator = __gnu_cxx::__normal_iterator<Edge*, std::vector<Edge, std::allocator<Edge> > >, _Compare = std::less<Edge>]'
/usr/lib/gcc/x86_64-pc-linux-gnu/3.4.0/include/g++-v3/bits/stl_queue.h:432: instantiated from `void std::priority_queue<_Tp, _Sequence, _Compare>::push(const typename _Sequence::value_type&) [with _Tp = Edge, _Sequence = std::vector<Edge, std::allocator<Edge> >, _Compare = std::less<Edge>]'
Node.cc:33: instantiated from here
/usr/lib/gcc/x86_64-pc-linux-gnu/3.4.0/include/g++-v3/bits/stl_function.h:227: error: no match for 'operator<' in '__x < __y'
Node.h:36: note: candidates are: bool operator<(Edge&, Edge&)

Any ideas? Thanks a lot

The last few error messages suggest you need to change the implementation of the '<' operator on Edges. Maybe it needs to take Edge arguments rather than ( Edge & ) arguments?

Alex

Wow - already quite some errors are gone - thanks - a few still remain - I'm really new to stl (Used it for the first time now - so I'm just posting the errors here:

/usr/lib/gcc/x86_64-pc-linux-gnu/3.4.0/include/g++-v3/bits/vector.tcc: In member function `Edge& Edge::operator=(const Edge&)':
/usr/lib/gcc/x86_64-pc-linux-gnu/3.4.0/include/g++-v3/bits/vector.tcc:238: instantiated from `void std::vector<_Tp, _Alloc>::_M_insert_aux(__gnu_cxx::__normal_iterator<_Tp*, std::vector<_Tp, _Alloc> >, const _Tp&) [with _Tp = Edge, _Alloc = std::allocator<Edge>]'
/usr/lib/gcc/x86_64-pc-linux-gnu/3.4.0/include/g++-v3/bits/stl_vector.h:564: instantiated from `void std::vector<_Tp, _Alloc>::push_back(const _Tp&) [with _Tp = Edge, _Alloc = std::allocator<Edge>]'
/usr/lib/gcc/x86_64-pc-linux-gnu/3.4.0/include/g++-v3/bits/stl_queue.h:431: instantiated from `void std::priority_queue<_Tp, _Sequence, _Compare>::push(const typename _Sequence::value_type&) [with _Tp = Edge, _Sequence = std::vector<Edge, std::allocator<Edge> >, _Compare = std::less<Edge>]'
Node.cc:33: instantiated from here
/usr/lib/gcc/x86_64-pc-linux-gnu/3.4.0/include/g++-v3/bits/vector.tcc:238: error: non-static reference member `Node&Edge::target', can't use default assignment operator

They still look very cryptic to me - but thanks already :D

Could you post your implementation of the '=' operator for Edge?

Alex

I just saw that - but I was wondering what it was needed for - I'll find out eventually

Thanks for the help