[Boost-users] BGL: std::map<Edge, int> needs the < operator

21 Apr 2006

      I'm trying to have a std::map where the key is an edge of a graph, but 
I get a compilation error.  My graph is:

typedef boost::adjacency_list ,
	property > > Graph;

And an edge:

typedef graph_traits<Graph>::edge_descriptor Edge;

Then I have a map:

	std::map m;

But when I try this:

	m[e] = 0

where e is of type Edge, then I get:

/usr/lib/gcc/i386-redhat-linux/3.4.4/../../../../include/c++/3.4.4/bits/stl_function.h:227: 
error: no match for 'operator<' in '__x < __y'

Can I use map with the Edge as the key type?  If so, what should I do?

Thanks for reading.

Best,
Irek

[Boost-users] BGL: std::map<Edge, int> needs the < operator

Irek Szczesniak