[Boost-users] Re: A boost.graph edge problem

From: Lars Kunert (lkunert_at_[hidden])
Date: 2004-09-23 07:15:53

Have a look at your compare operator!
It orders two pairs of values (A,B)(C,D)
like this:
(A<B) || (!(A<B) && (C<D))
this expession equals:
(A<B) || (C<D)
lets consider the test case:
(1,2) (2,1)
Your operator will return return true in whatever order this
pair is compared...
I think an operator like
(A<B) || ((A==B) && (C<D))
will help
> ...
> typedef multiset<DataEdge,ltSubgraph> Edges;
> ...
> struct ltSubgraph : public 
> std::binary_function<DataEdge,DataEdge,bool>
> {
>   bool operator() (const DataEdge& s1, const DataEdge& s2) const
>   {
>     return s1.m_source < s2.m_source ||
>      (!(s1.m_source < s2.m_source) && s1.m_target < s2.m_target);
>   }
> };