/usr/lib/gcc/i486-linux-gnu/4.1.2/../../../../include/c++/4.1.2/bits/stl_function.h: In member function &#8216;bool std::less<_Tp>::operator()(const _Tp&, const _Tp&) const [with _Tp = HNode]&#8217;:
/usr/lib/gcc/i486-linux-gnu/4.1.2/../../../../include/c++/4.1.2/bits/stl_heap.h:279:   instantiated from &#8216;void std::__adjust_heap(_RandomAccessIterator, _Distance, _Distance, _Tp, _Compare) [with _RandomAccessIterator = __gnu_cxx::__normal_iterator<HNode*, std::vector<HNode, std::allocator<HNode> > >, _Distance = int, _Tp = HNode, _Compare = std::less<HNode>]&#8217;
/usr/lib/gcc/i486-linux-gnu/4.1.2/../../../../include/c++/4.1.2/bits/stl_heap.h:404:   instantiated from &#8216;void std::make_heap(_RandomAccessIterator, _RandomAccessIterator, _Compare) [with _RandomAccessIterator = __gnu_cxx::__normal_iterator<HNode*, std::vector<HNode, std::allocator<HNode> > >, _Compare = std::less<HNode>]&#8217;
/usr/lib/gcc/i486-linux-gnu/4.1.2/../../../../include/c++/4.1.2/bits/stl_queue.h:367:   instantiated from &#8216;s/usr/lib/gcc/i486-linux-gnu/4.1.2/../../../../include/c++/4.1.2/bits/stl_function.h: In member function &#8216;bool std::less<_Tp>::operator()(const _Tp&, const _Tp&) const [with _Tp = HNode]&#8217;:
/usr/lib/gcc/i486-linux-gnu/4.1.2/../../../../include/c++/4.1.2/bits/stl_heap.h:279:   instantiated from &#8216;void std::__adjust_heap(_RandomAccessIterator, _Distance, _Distance, _Tp, _Compare) [with _RandomAccessIterator = __gnu_cxx::__normal_iterator<HNode*, std::vector<HNode, std::allocator<HNode> > >, _Distance = int, _Tp = HNode, _Compare = std::less<HNode>]&#8217;
/usr/lib/gcc/i486-linux-gnu/4.1.2/../../../../include/c++/4.1.2/bits/stl_heap.h:404:   instantiated from &#8216;void std::make_heap(_RandomAccessIterator, _RandomAccessIterator, _Compare) [with _RandomAccessIterator = __gnu_cxx::__normal_iterator<HNode*, std::vector<HNode, std::allocator<HNode> > >, _Compare = std::less<HNode>]&#8217;
/usr/lib/gcc/i486-linux-gnu/4.1.2/../../../../include/c++/4.1.2/bits/stl_queue.h:367:   instantiated from &#8216;std::priority_queue<_Tp, _Sequence, _Compare>::priority_queue(const _Compare&, const _Sequence&) [with _Tp = HNode, _Sequence = std::vector<HNode, std::allocator<HNode> >, _Compare = std::less<HNode>]&#8217;
HuffmanTree.cc:5:   instantiated from here
/usr/lib/gcc/i486-linux-gnu/4.1.2/../../../../include/c++/4.1.2/bits/stl_function.h:227: error: no match for &#8216;operator<&#8217; in &#8216;__x < __y&#8217;
HNode.h:21: note: candidates are: bool HNode::operator<(HNode&)
make: *** [HuffmanTree.o] Error 1
td::priority_queue<_Tp, _Sequence, _Compare>::priority_queue(const _Compare&, const _Sequence&) [with _Tp = HNode, _Sequence = std::vector<HNode, std::allocator<HNode> >, _Compare = std::less<HNode>]&#8217;
HuffmanTree.cc:5:   instantiated from here
/usr/lib/gcc/i486-linux-gnu/4.1.2/../../../../include/c++/4.1.2/bits/stl_function.h:227: error: no match for &#8216;operator<&#8217; in &#8216;__x < __y&#8217;
HNode.h:21: note: candidates are: bool HNode::operator<(HNode&)
make: *** [HuffmanTree.o] Error 1