- Boost-users - lists.preview.boost.org

Boost Graph Library(biconnected_components) issue
by Meghana.M Reddy 07 May '18

07 May '18

Hi, I am working on the Boost Graph Library, currently trying to create an interface of the biconnected_components method to a Python code. I used the example code available here <https://www.boost.org/doc/libs/1_67_0/libs/graph/example/biconnected_compon…> for the method and modified it for my purpose. The template of the method is here <https://www.boost.org/doc/libs/1_67_0/libs/graph/doc/biconnected_components…>. The final code seems fine but I get an error while compiling it. And the errors are related to adjacency.hpp which I have not changed so I'm confused as to what the exact problem is. Hoping someone can help me out. My code: class BoostGraph { private: typedef typename boost::adjacency_list< OutEdgeListS, VertexListS, DirectedS, boost::property<boost::vertex_index_t, v_index>, EdgeProperty, boost::no_property, EdgeListS> adjacency_list; typedef typename boost::property_map<adjacency_list, boost::edge_index_t>::type components; public: adjacency_list graph; std::vector<v_index> bc_tree() { components components_bc = get(boost::edge_index, graph); std::size_t num_comps = biconnected_components(graph, components_bc); std::cerr << "Found " << num_comps << " biconnected components.\n"; std::vector<vertex_descriptor> art_points; articulation_points(graph, std::back_inserter(art_points)); std::cerr << "Found " << art_points.size() << " articulation points.\n"; std::vector<v_index> to_return; return to_return; } The error I'm getting: build/cythonized/sage/graphs/base/boost_graph.cpp:3730:26: required from here /home/meghana/Documents/sage_gsoc/sage_may/sage/local/ include/boost/graph/detail/adjacency_list.hpp:2696:29: error: forming reference to void typedef value_type& reference; ^ /home/meghana/Documents/sage_gsoc/sage_may/sage/local/ include/boost/graph/detail/adjacency_list.hpp:2697:35: error: forming reference to void typedef const value_type& const_reference; ^ /home/meghana/Documents/sage_gsoc/sage_may/sage/local/ include/boost/graph/detail/adjacency_list.hpp:2701:61: error: forming reference to void typename Graph::vertex_descriptor,Property,Tag> type; ^ /home/meghana/Documents/sage_gsoc/sage_may/sage/local/ include/boost/graph/detail/adjacency_list.hpp:2704:68: error: forming reference to void typename Graph::vertex_descriptor,const Property, Tag> const_type; ^ error: command 'gcc' failed with exit status 1 Makefile:33: recipe for target 'sage' failed make: *** [sage] Error 1 Thank you, Meghana

1 0

Installing pre-built binaries on Windows with Docker
by Matthew Berry 04 May '18

04 May '18

Hi, I tried installing pre-built 1.67 binaries from https://dl.bintray.com/boostorg/release/1.67.0/binaries/ in a Windows Server Docker container but am running into an issue where the installation does not complete. I ran the installer exe in silent mode. A lot of the files including headers are installed, but not the lib directory with the binaries. The Inno Setup log does not indicate an error, it just stops writing in the middle of the installation. Does anyone know why installation does not complete? Has anyone been able to install pre-built libraries in a Windows Docker container? Any help would be appreciated. Thanks, Matt

2 1

Why is BOOST_OS_WINDOWS defined on Linux
by David Demelier 04 May '18

04 May '18

Hello, Everything is in the title, the following code compiles and shows "Windows" even though I'm running Fedora 28. I can't understand. #include <iostream> #include <boost/predef.h> int main() { #if defined(BOOST_OS_WINDOWS) puts("Windows"); #endif } I'm using Boost 1.66 with GCC 8.0.1. Regards, -- David

3 5

Bi-Directional Links in call to Push-Relabel Max Flow (UNCLASSIFIED)
by Glover, Anthony E CTR USARMY RDECOM (US) 03 May '18

03 May '18

CLASSIFICATION: UNCLASSIFIED Hello, I am new to the Boost Graph library and had a question concerning the Push-Relabel Max Flow method. From the documentation, it states: The CapacityEdgeMap argument cap must map each edge in E to a positive number, and each edge in ET to 0. >From looking at the examples provided, it appears that an edge is added with some non-zero capacity and then the reverse edge is created with a capacity of 0 as the documentation states is needed. However, if I truly want a reverse edge with non-zero capacity, it appears that I have to create a second pair of edges going the other direction. I end up creating 4 total edges to handle the bi-directional flow capacity. Is that truly how the graph should be configured in order to use the method? Maybe I'm just not using it as designed. Thank You, Tony CLASSIFICATION: UNCLASSIFIED

1 0

Veracode Scan
by Abhijit Dutta 03 May '18

03 May '18

Hi There, As part of release practice in our org., we have run Veracode (static) scan on our application which uses BOOST. We got good amount of error pointing to the BOOST libraries. Detecting the false positives and fixing the code will be a tedious task. So, want to know if anyone in the community has faced such situations and want to share their experience on resolving those. ~Thanx Abhijit

2 2

help
by Radekkostra＠seznam.cz 30 Apr '18

30 Apr '18

hello, i am trying to build boost, but i have problems. First is in log(bootstrap.log - could not find "vswhere") and second is when compiling boost(this command :.\b2 --toolset=msvc link=shared,static address -model=64 --with-system --with-filesystem -j 4(5 failed,12skipped,79 updated).

2 2

[Process] Help needed with boost::process::extend::on_*
by Günter Berner 26 Apr '18

26 Apr '18

I am using boost::process::child to create a child process: boost::process::child child("foo"); This works fine so far (on Linux + Windows). Now i want to use a handler which is executed during the fork process: boost::process::child child("foo", boost::process::extend::on_setup = [](auto& exec) { // ... }); This also works fine - as long as a more or less up-to-date C++ compiler or C++ standard. Since g++-4.8.5 (which I have to use) does not support auto template deduction for lambdas, i have to replace the lambda parameter type with a concrete type. boost::process::child child("foo", boost::process::extend::on_setup = [](<WHAT_GOES_HERE?>& exec) { // ... }); Boost.Process documentation only uses the modern approach with auto template deduction. I simply cannot find an example/documentation where the concrete types are shown. Thanks.

1 0

failed coversion
by Markel, Joseph 25 Apr '18

25 Apr '18

Is there a way to get the int value by performing division on boost::any variables? #include <boost/any.hpp> int main(void) { boost::any a = 10; std::cout << boost::any_cast<int>(a) << std::endl; boost::any s = 2.5; // scaling factor // scale the value a = boost::any_cast<int>(a)/boost::any_cast<float>(s); std::cout << boost::any_cast<int>(a) << std::endl; } This throws the error boost::bad_any_cast: failed conversion using boost::any_cast Thanks CONFIDENTIALITY NOTICE: This e-mail communication and any attachments may contain proprietary and privileged information for the use of the designated recipients named above. Any unauthorized review, use, disclosure or distribution is prohibited. If you are not the intended recipient, please contact the sender by reply e-mail and destroy all copies of the original message.

2 1

[multiprecision] static_cast<cpp_bin_float_100> gives strange values.
by Vögl, Christian 20 Apr '18

20 Apr '18

Hi everyone. The following Situation: I tried to improve the accuracy of a numerical function by replacing all double variables with cpp_bin_float_100. The parameters of this function contain two 3-element double arrays, which I convert to cpp_bin_float_100 by the following function: static void equal(cpp_bin_float_100* a, double* b) { for(int i=0; i<3;i++) { a[i]=static_cast<cpp_bin_float_100>(b[i]); } } the third element seems to be converted correctly, the first and second are totally off. (e. g. 100 -> 1.5625)

2 1

[asio] Using struct ip_mreqn to joing multicast group
by Klebsch, Mario 20 Apr '18

20 Apr '18

Hi, I need to receive multicasts on multiple interfaces and handle them differently, depending on the network interface they arrived on. For each network interface, I create an UDP socket and I use Socket.set_option(boost::asio::ip::multicast::join_group(MCastReqAddr.to_v4(), LocalAddr.to_v4() ), ec); to join the multicast group. LocalAddr is the local IPv4 address of the interface. Unfortunately, I receive each incoming multicast message on each socket. I found, that boost::asio::ip::multicast::join_group uses struct ip_mreq, where the multicast address and the local address can be specified. On linux the man page on IP_ADD_MEMBERSHIP tells to use struct ip_mreqn. This structure had an additional member imr_ifindex. The documentation is not very clear about the difference between imr_address and imr_ifindex. So, I want to try it out and wonder, whether boost::asio supports using struct ip_mreqn for IP_ADD_MEMBERSHIP. If not, does anybody know, how to write my own class to be used with Socket.set_option? 73, Mario -- Mario Klebsch Actia I+ME GmbH Mario.klebsch(a)ime-actia.de<mailto:Mario.klebsch@ime-actia.de> Dresdenstrasse 17/18 Fon: +49 531 38 701 716 38124 Braunschweig Fax: +49 531 38 701 88 Germany

1 0