Boost_Reference_Manual_Page_141_code.cpp

#include <boost/graph/adjacency_list.hpp>

template <typename DirectedGraph>
void directed_graph_demo(){
	/*The value of V is not imp, we need it just to pass into constructor at "UndirectedGraph undigraph(V);" to initialize it.
	Later on we can add as many vertices as we want*/
	const int V = 0;
	DirectedGraph digraph(V);
	typename boost::graph_traits<DirectedGraph>::vertex_descriptor u, v;
	//edge_property_type Weight will be used to pass weight values for each edge
	typedef typename DirectedGraph::edge_property_type Weight;
	//This weight obj will be used to extract the weight values for each edge later on
	typename boost::property_map<DirectedGraph, boost::edge_weight_t>::type weight = get(boost::edge_weight, digraph);
	typename boost::graph_traits<DirectedGraph>::edge_descriptor e1, e2;
	bool found;

	u = vertex(0, digraph);
	v = vertex(1, digraph);
	add_edge(u, v, Weight(1.2), digraph);
	add_edge(v, u, Weight(2.4), digraph);

	tie(e1, found) = edge(u, v, digraph);
	tie(e2, found) = edge(v, u, digraph);

	//Following "std::boolalpha << (e1==e2)" will compare the two edges are return a boolean type instead
	std::cout<< std::boolalpha << (e1==e2) << std::endl;
	std::cout<< get(weight, e1) << std::endl;
	std::cout<< get(weight, e2) << std::endl;
}

int main(){
	//Here we are making a property obj.
	typedef boost::property < boost::edge_weight_t, double >Weight;
	//Passing above defined property obj into adjacency_list as edge's weight
	typedef boost::adjacency_list<boost::listS, boost::vecS, boost::directedS,
			boost::no_property, Weight> DirectedGraph;

	directed_graph_demo<DirectedGraph>();
}