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[ptr_map]iterator::reference is not a reference
by Bill Buklis 11 Oct '07

11 Oct '07

I found what seems to be an inconsistency in ptr_map in version 1.34.1 versus 1.33.1. The "reference" typedef in 1.34.1 does not appear to be a reference. The following code illustrates what I mean: typedef std::map<int, int> STDMAP; typedef boost::ptr_map<int, int> PTRMAP; bool isrefstdmap = boost::is_reference<STDMAP::iterator::reference>::value; bool isrefstdbase = boost::is_reference<STDMAP::reference>::value; bool isrefptrmap = boost::is_reference<PTRMAP::iterator::reference>::value; bool isrefptrbase = boost::is_reference<PTRMAP::reference>::value; In version 1.33.1 all bool values equate to true, while in 1.34.1 ptr_map evaluates to false. In case the compiler makes a difference, I'm using VC++ 2005. -- Bill Buklis --

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[boost][range] fusion::begin and boost::begin dont play nice
by John Femiani 11 Oct '07

11 Oct '07

I am using g++ (GCC) 3.4.2 (mingw-special) and when I use the namespace boost::fusion it causes boost range to break. Consider the toy program 'main.cpp', which is attached and also listed below: ----------------------------------------------------------------------- #include <iostream> using namespace std; #include <boost/fusion/sequence/container/vector.hpp> #include <boost/range.hpp> #include <list> int main() { using namespace boost::fusion; using namespace boost; std::list<int> ints; typedef boost::range_iterator<std::list<int> >::type iterator_t; for (iterator_t i = begin(ints); i != end(ints); ++i){ cout << * i << endl; } return 0; } -------------------------------------------------------------------- This program fails to compile with many errors, the first is C:/MSYS/1.0/include/boost/fusion/sequence/intrinsic/begin.hpp:56: error: invalid use of undefined type `struct boost::fusion::extension::begin_impl<boost::fusion::non_fusion_tag>::app ly<const std::list<int, std::allocator<int> > >' If I remove 'using namespace boost::fusion' then everything compiles. This toy program demonstrates an error I got when trying to compile a function that involved both a fusion::vector and std::list. It was easy to work around it in my case by explicitly saying boost::fusion::begin instead of using the namespace, but I suspect that this is still a bug. Please let me know if I misunderstood the correct way to use fusion or range. Thanx, -- John

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Assigning a var() to another var() in a lambda function
by Peter Waller 11 Oct '07

11 Oct '07

Why does this not compile? Should it? It seems quite similar to code found in the section `Naming delayed constants and variables' in the manual at http://www.boost.org/doc/html/lambda/le_in_details.html #include <lambda/lambda.hpp> using namespace boost::lambda; float i = 5, j = 0; var_type<float>::type vi(var(i)), vj(var(j)); #line 172 (vi = vj); The error I get: /usr/include/boost/lambda/detail/lambda_functor_base.hpp: In member function 'boost::lambda::identity<Float_t&>& boost::lambda::identity<Float_t&>::operator=(const boost::lambda::identity<Float_t&>&)': /usr/include/boost/lambda/detail/lambda_functor_base.hpp:23: error: non-static reference member 'Float_t& boost::lambda::identity<Float_t&>::elem', can't use default assignment operator /usr/include/boost/lambda/detail/lambda_functors.hpp: In member function 'boost::lambda::lambda_functor<boost::lambda::identity<Float_t&> >& boost::lambda::lambda_functor<boost::lambda::identity<Float_t&> >::operator=(const boost::lambda::lambda_functor<boost::lambda::identity<Float_t&> >&)': /usr/include/boost/lambda/detail/lambda_functors.hpp:113: note: synthesized method 'boost::lambda::identity<Float_t&>& boost::lambda::identity<Float_t&>::operator=(const boost::lambda::identity<Float_t&>&)' first required here zzNtuple.C: In function 'int main(int, char**)': zzNtuple.C:173: note: synthesized method 'boost::lambda::lambda_functor<boost::lambda::identity<Float_t&> >& boost::lambda::lambda_functor<boost::lambda::identity<Float_t&> >::operator=(const boost::lambda::lambda_functor<boost::lambda::identity<Float_t&> >&)' first required here make: *** [zzNtuple] Error 1 g++ (GCC) 4.1.2 boost 1.34.1 Thanks in advance, - Peter

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Boost 1.35?
by Matt Wharton 11 Oct '07

11 Oct '07

Hello, Does anyone have a _rough_ timetable for when boost version 1.35 will be formally released? Apologies in advance if this question has already been answered or if this is the wrong venue for it. Thanks, -Matt

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Re: [Boost-users] Boost Spirit and C++/CLI
by Hansi Hansi 10 Oct '07

10 Oct '07

What is exactly the error? Which project type you have? What is your entrypoint? Best regards Hansjörg __________________________________________________________________________ Erweitern Sie FreeMail zu einem noch leistungsstärkeren E-Mail-Postfach! Mehr Infos unter http://produkte.web.de/club/?mc=021131

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Re: [Boost-users] regex_search in std::string
by Troy Alexander 10 Oct '07

10 Oct '07

Thanks. That did it. I was focusing on the string to match not the return type. Makes since that they need to be the same type. Troy -----Original Message----- From: boost-users-bounces(a)lists.boost.org [mailto:boost-users-bounces@lists.boost.org] On Behalf Of John Maddock Sent: Wednesday, October 10, 2007 2:44 AM To: boost-users(a)lists.boost.org Subject: Re: [Boost-users] regex_search in std::string Troy Alexander wrote: > The 1st regex_search looking at input_line char[] works Ok it's the > 2nd one looking at date_and_time_s std::string that gets the error. > If I remark out the 2nd one the program builds and I watch the > input_line doing what it should in the debugger. > > Also this code used to work before I upgraded from Visual C++6 to > Visual C++8 and from bost_1_33_1 to boost_1_34_0. I don't know if it > was the change in compiler or the boost lib that broke this. In VC6 this worked "by accident" because const char* and std::string::const_iterator were the same type. That's not true in general, and you should use boost::smatch as the match_results type for use with std::string's. HTH, John. _______________________________________________ Boost-users mailing list Boost-users(a)lists.boost.org http://lists.boost.org/mailman/listinfo.cgi/boost-users

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[BGL] maximum flow through push_relabel_max_flow
by "Alejandro M. Aragón" 10 Oct '07

10 Oct '07

Hello all, I've been working with the Edmunds & Karp maximum flow algorithm in the BGL for some time without any problems. However, I realized that I could do better in time complexity by moving to the push_relabel_max_flow algorithm so I gave it a try. I've been trying to figure out what the problem with my code is for the entire day without success. I was wondering if someone could tell me what is my mistake. It is a very simple problem, four vertices, four edges, the result from the algorithm should be two: 2--------1 | | | | | | 0--------3 Source is 0, target is 1, all edges have unit capacity. The code is: void compute_max_flow(Graph* g_) { // obtain number of vertices in undirected graph size_t n = num_vertices(*g_); typedef adjacency_list_traits<vecS, vecS, directedS> Traits; typedef adjacency_list<listS, vecS, directedS, property<vertex_index_t, int>, property<edge_capacity_t, int, property<edge_residual_capacity_t, int, property<edge_reverse_t, Traits::edge_descriptor> > > > FlowGraph; typedef graph_traits<FlowGraph>::edge_descriptor EdgeFlow; FlowGraph g(num_vertices(*this->g_)); property_map<FlowGraph, vertex_index_t>::type indexmap = get(vertex_index, g); property_map<FlowGraph, edge_capacity_t>::type capacity = get(edge_capacity, g); property_map<FlowGraph, edge_reverse_t>::type rev = get(edge_reverse, g); property_map<FlowGraph, edge_residual_capacity_t>::type residual_capacity = get(edge_residual_capacity, g); Traits::vertex_descriptor s, t; EdgeFlow e1,e2; bool in1,in2; // add edges, reverse edges and capacities to new graph for flow computation edge_iter ei,ei_end; for (tie(ei,ei_end) = edges(*g_); ei != ei_end; ++ei) { // obtain vertices in the original graph vertex u = source(*ei, *g_); vertex v = target(*ei, *g_); // insert edges in new graph and add unit capacities tie(e1, in1) = add_edge(u,v,g); tie(e2, in2) = add_edge(v,u,g); if(in1 && in2) { // assign reverse edges to property map rev[e1] = e2; rev[e2] = e1; capacity[e1] = 1; capacity[e2] = 0; } } graph_traits<FlowGraph>::vertex_iterator vvi,vvi_end; for(tie(vvi,vvi_end) = vertices(g); vvi!=vvi_end; ++vvi) { cout<<"index -> "<<indexmap[*vvi]<<endl; } graph_traits<FlowGraph>::edge_iterator eei,eei_end; for(tie(eei,eei_end) = edges(g); eei!=eei_end; ++eei) { cout<<"edge -> "<<*eei<<endl; cout<<"capacity -> "<<capacity[*eei]<<endl; cout<<"rev -> "<<rev[*eei]<<endl; } int flow = push_relabel_max_flow(g, 0, 1, capacity, residual_capacity, rev, indexmap); cout<<"flow -> "<<flow<<endl; } Results in: index -> 0 index -> 1 index -> 2 index -> 3 edge -> (0,2) capacity -> 1 rev -> (2,0) edge -> (0,3) capacity -> 1 rev -> (3,0) edge -> (1,2) capacity -> 1 rev -> (2,1) edge -> (1,3) capacity -> 1 rev -> (3,1) edge -> (2,0) capacity -> 0 rev -> (0,2) edge -> (2,1) capacity -> 0 rev -> (1,2) edge -> (3,0) capacity -> 0 rev -> (0,3) edge -> (3,1) capacity -> 0 rev -> (1,3) flow -> 0 I would appreciate any inputs on this. Thank you, a²

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Usage of Transitive_closure().
by Ning Ruan 10 Oct '07

10 Oct '07

my code to use transitive_closure(): Graph tc; VertexIndexMap index_map = get(&VertexProp::id, g); vector<Vertex> to_tc_vec(num_vertices(g)); iterator_property_map<Vertex*, VertexIndexMap, Vertex, Vertex&> g_to_tc_map(&to_tc_vec[0], index_map); transitive_closure(graph, tc, g_to_tc_map, (index_map)); I use print_graph(tc, get(&VertexProp::id, tc) to print the transitive graph, then it shows: 0 --> 0 0 0 0 0 0 0 0 0 --> 0 0 0 --> 0 --> 0 0 0 0 0 0 0 0 0 --> 0 --> 0 --> 0 0 0 0 --> 0 0 0 0 0 0 0 0 the result miss the id of vertex, what 's the problem. my original graph g is correcet: 0 --> 1 2 3 1 --> 4 5 2 --> 3 --> 6 7 4 --> 5 --> 6 --> 1 7 --> 0

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regex_search in std::string
by Troy Alexander 10 Oct '07

10 Oct '07

I am struggling with a regex in some code of mine. I want to use regex_search to look for a match in a std::string, but my code will not build. This is a snippet of what I am trying to do. using namespace std; string in_file_name_s; string date_and_time_s; string day_s; char input_line[5000]; boost::regex re_date_time("(.*-.*-.*:.*:.*),.*,.*,.*,.*,.*,.*,.*,.*,"); boost::regex re_pices_date_time("(.*)\\-(.*)\\-(.*) (.*)"); boost::cmatch match; while (inFile.getline(input_line , 5000)) { if (boost::regex_search(input_line, match , re_date_time )) { date_and_time_s = match[1]; if (boost::regex_search(date_and_time_s , match , re_pices_date_time )) { day_s = match[1]; } } } When I compile I get the following error error C2784: 'bool boost::regex_search(const std::basic_string<charT,ST,SA> &,const boost::basic_regex<charT,traits> &,boost::regex_constants::match_flag_type)' : could not deduce template argument for 'const boost::basic_regex<charT,traits> &' from 'boost::cmatch' The 1st regex_search looking at input_line char[] works Ok it's the 2nd one looking at date_and_time_s std::string that gets the error. If I remark out the 2nd one the program builds and I watch the input_line doing what it should in the debugger. Also this code used to work before I upgraded from Visual C++6 to Visual C++8 and from bost_1_33_1 to boost_1_34_0. I don't know if it was the change in compiler or the boost lib that broke this. Thanks in advance for your help. Troy

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Re: [Boost-users] Boost::regex causes runtime errors with CLR
by Hansi Hansi 10 Oct '07

10 Oct '07

Hello, In VS2005 is a problem with the Initializing of the CRT when you have a .net application. Normally it helps when you use as entry point '?mainCRTStartupStrArray@@$$FYMHP$01AP$AAVString@System@@@Z'. I hope this helps. Best regards Hansjörg _____________________________________________________________________ Der WEB.DE SmartSurfer hilft bis zu 70% Ihrer Onlinekosten zu sparen! http://smartsurfer.web.de/?mc=100071&distributionid=000000000066

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