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vertex structure
by bayer.tomas＠upcmail.cz 24 Nov '07

24 Nov '07

Hello, I have the problem with the vertex structure definition. I don´t know, how to create graph with variable vertices count without vertices renaming. Source graph: (n=5 vertices) Edges { E(130, 27), E(1, 83), E(1, 204), E(27, 1), E(27, 130), E(83, 204), E(204, 130)}; To find minimal spannig tree using Prim leeds to vertices renaming <0,n-1>. Renamed graph: Edges { E(0, 2), E(1, 3), E(1, 4), E(2, 1), E(2, 0), E(3, 4), E(4, 0)}. But it is very uncomfortable. How could I use original vertices number in graph definition? Thanks Tomas My source code: #include <boost/config.hpp> #include <boost/utility.hpp> #include <boost/graph/adjacency_list.hpp> #include <boost/graph/prim_minimum_spanning_tree.hpp> #include <boost/graph/subgraph.hpp> typedef boost::adjacency_list_traits< boost::vecS, boost::vecS, boost::undirectedS >::vertex_descriptor vertex_descriptor; typedef boost::property<boost::vertex_color_t, boost::default_color_type, boost::property< boost::vertex_predecessor_t, vertex_descriptor > > VertexProperty; typedef boost::property<boost::edge_color_t, boost::default_color_type, boost::property<boost::edge_weight_t, int, boost::property<boost::edge_index_t, int > > > EdgeProperty; typedef boost::subgraph< boost::adjacency_list<boost::vecS, boost::vecS, boost::undirectedS, VertexProperty, EdgeProperty > > Graph; typedef boost::graph_traits < Graph >::edge_descriptor Edge; int main(void) { int num=5; Graph g(num); boost::property_map<Graph, boost::edge_weight_t>::type weightmap = boost::get(boost::edge_weight, g); Edge e; bool inserted; //Here I would like to use original vertices numbers boost::tie(e, inserted) = boost::add_edge(0, 2, g); weightmap[e] = 1; boost::tie(e, inserted) = boost::add_edge(1, 3, g); weightmap[e] = 1; boost::tie(e, inserted) = boost::add_edge(1, 4, g); weightmap[e] = 1; boost::tie(e, inserted) = boost::add_edge(2, 1, g); weightmap[e] = 1; boost::tie(e, inserted) = boost::add_edge(2, 0, g); weightmap[e] = 1; boost::tie(e, inserted) = boost::add_edge(3, 4, g); weightmap[e] = 1; boost::tie(e, inserted) = boost::add_edge(4, 0, g); weightmap[e] = 1; std::vector < boost::graph_traits < Graph >::vertex_descriptor > p(num_vertices(g)); boost::prim_minimum_spanning_tree(g, &p[0]); for (std::size_t i = 0; i != p.size(); ++i) if (p[i] != i) std::cout << "parent[" << i << "] = " << p[i] << std::endl; else std::cout << "parent[" << i << "] = no parent" << std::endl; }

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(newbie) problem using boost::regex on kubuntu 7.10
by canx11 24 Nov '07

24 Nov '07

Hello, i am new to c++ coding and for practicing i want to rewrite some of my old perl scripts that use regular expressions in c++. So i installed libboost for regex version 1.34.1 on my workstation (using a kubuntu package). Unfortunatley even the most simple program i can think of does not want to compile: #include <iostream> #include <cstdlib> #include <boost/regex.hpp> using namespace boost; using namespace std; int main(int argc, char *argv[]) { boost::regex(".*"); cout << "test\n"; return 0; } ...giving me: [...] testapp.o: In function `boost::basic_regex<char, boost::regex_traits<char, boost::cpp_regex_traits<char> > >::assign(char const*, char const*, unsigned int)': /usr/include/boost/regex/v4/basic_regex.hpp:255: undefined reference to `boost::basic_regex<char, boost::regex_traits<char, boost::cpp_regex_traits<char> > >::do_assign(char const*, char const*, unsigned int)' collect2: ld returned 1 exit status [...] Anyhow if i am doing int main(int argc, char *argv[]) { boost::regex(); cout << "test\n"; return 0; } withouth passing a regex condition it compiles successful...Yes i know this short programm does not give any meaningful functionality but i just want to demonstrate that the intialization of the basic_regex fails on my machine. Do i have problem with my libboost installation or just a simple syntax error here? regards Jan

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stlport and visual studio 8.0
by beelzebob999-libcurl＠yahoo.com 24 Nov '07

24 Nov '07

I have looked and looked and looked... sorry to ask what must be a very newbie question, but I can't find an answer anywhere in the documentation. How does one go about compiling boost with stlport? My platform is windows xp sp2, visual studio 8.0. Also, is it even worthwhile to do so? We are seeing significant slowdowns in our code due to what we think is lock contention in the standard library that ships with visual studio 8.0, so we are looking for alternatives. Does STLport run better in a multithreaded environment than the stl that comes with visual studio 8.0? Thanks.

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Threads
by Rij 24 Nov '07

24 Nov '07

I tried putting in a while(1) loop in operator(). Same error.

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Boost semaphore with condition variable
by Fabian Sturm 23 Nov '07

23 Nov '07

Hi! I have a quite simple problem, but I still lack a nice implementation in C++ with boost. My problem is, that I have two threads A and B and thread A needs some information that B will calculate at runtime. Therefore I need some kind of synchronization. So my first attempt was to use a mutex and a condition variable: Thread A: boost::thread::mutex::scoped_lock lock ( mMutex ); mConditionVar.wait ( lock ); Thread B: mConditionVar.notify_one (); This works nice as long as thread A already started waiting on the condition before thread B finished providing it. Otherwise the notify will be lost. So my second attempt was to use a barrier: Init barrier with count 2 Thread A: mBarrier.wait (); Thread B: mBarrier.wait (); This works fine and A will wait until the result is available and it doens't matter if it starts waiting before or after B finished calculaating. But the problem now is that B also needs to wait for A to reach the point in execution. So if I just want to signal thread A from thread B that some point was reached. I don't know how to do it with boost. If I would have a semaphore available I could init it with 0 and thread A tries to decrement it while thread B will increment it once it reached the point. But http://www.boost.org/doc/html/thread/faq.html#id1747096 says: "Semaphore was removed as too error prone. The same effect can be achieved with greater safety by the combination of a mutex and a condition variable." So how exactly is this achieved with the mutex and condition variable? I always only come up with a mutex, condition variable and a bool which all three must be shared between both threads. I would greatly appreciate any suggestions! Thanks, Fabian

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boost::thread and dual (quad) core CPU(s)
by misiu 23 Nov '07

23 Nov '07

Hello, I've developed small application which has a few threads. So far I'm using only single CPU (one core) and my question is: what will happen if I'm using more CPUs (or cores)? Whether threads will be automatically executed on different CPUs in parallel or not? If not what is a solution to run them in parallel? Unfortunately currently I have no access to multi-processor machine to check it myself. Regards, Bartek

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[boost-users] [boost pointers containers and stl]
by chun ping wang 23 Nov '07

23 Nov '07

Hi how would I use these following function with boost pointers containers. a.) stl's set_intersection and set_Unions. b.) binary_search

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[mpl] cross product of 2 sequences
by Roman Perepelitsa 23 Nov '07

23 Nov '07

Hello, I need metafunction cross_product, which should transform 2 sequences to a sequence of pairs. Example: typedef list<int, char> l1; typedef list<int *, char *> l2; typedef cross_product<l1, l2>::type c; typedef list< pair<int, int *>, pair<int, char *>, pair<char, int *>, pair<char, char *> > e; BOOST_MPL_ASSERT((equal<c, e>)); The best definition I came up with is the following: template <class T, class R> struct product : transform<R, pair<T, _1> > { }; template <class R1, class R2> struct cross_product : fold< typename transform<R1, product<_1, R2> >::type, list<>, joint_view<_1, _2> > { }; Is there a better way to do it? How can I get rid of 'struct product' and implement it as one metafunction? Regards, Roman Perepelitsa Deutsche Bank Moscow +7 (495) 660-74-08 --- This e-mail may contain confidential and/or privileged information. If you are not the intended recipient (or have received this e-mail in error) please notify the sender immediately and delete this e-mail. Any unauthorized copying, disclosure or distribution of the material in this e-mail is strictly forbidden. Please refer to http://www.db.com/en/content/eu_disclosures.htm for additional EU corporate and regulatory disclosures.

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Best way to create objects of arbitrary length and types
by Roman Morokutti 23 Nov '07

23 Nov '07

Hi, what would be the best solution to create objects of variable length and arbitrary types in C++ which are best in performance and size respectively. Or is there a solution in boost for this kind of problem anyway? These objects would be written in a queue for asynchron processing. Thanks in advance. Roman

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Error when trying to use johnson_all_pairs_shortest_paths ( ) function
by Sangameshwar Patil 23 Nov '07

23 Nov '07

Hi, I am getting following error when trying to use the johnson_all_pairs_shortest_paths( ) function in boost graph library (BGL). "no matching function for call to johnson_all_pairs_shortest_paths(boost::adjacency_list<boost::setS, boost::vecS, boost::bidirectionalS, boost::property<boost::vertex_name_t, std::string, boost::no_property>, boost::property<boost::edge_weight_t, int, boost::property<boost::edge_weight2_t, int, boost::no_property> >, boost::no_property, boost::listS>&, int[((unsigned int)((int)V))][((unsigned int)((int)V))], boost::bgl_named_params<int*, boost::vertex_distance_t, boost::no_property>) " relevant variable declarations & typedefs are: typedef adjacency_list <setS, vecS, bidirectionalS, property <vertex_name_t, std::string>, \ property <edge_weight_t, int, property< edge_weight2_t, int > > > Graph; ..... // Graph g is constructed ..... int V = num_vertices(g); std::vector < int >d_j(V, (std::numeric_limits < int >::max)()); int D[V][V]; ..... // call Johnson's all pair shortest path algo. johnson_all_pairs_shortest_paths(g, D, distance_map(&d_j[0])); Do let me know if any more info is reqd. I would greatly appreciate any help/suggestions. Thanks and regards, Sangam =====-----=====-----===== Notice: The information contained in this e-mail message and/or attachments to it may contain confidential or privileged information. If you are not the intended recipient, any dissemination, use, review, distribution, printing or copying of the information contained in this e-mail message and/or attachments to it are strictly prohibited. If you have received this communication in error, please notify us by reply e-mail or telephone and immediately and permanently delete the message and any attachments. Thank you

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