November 2008 - Boost-users - lists.preview.boost.org

[boost::string_algo] Minor documentation error
by Anders Dalvander 29 Nov '08

29 Nov '08

Hi, I found a minor error in the Boost String Algorithms documentation for Boost 1.37. http://www.boost.org/doc/libs/1_37_0/doc/html/boost/algorithm/is_less.html Documentation states "Compare two operands using > operator", when implementation use < operator. http://www.boost.org/doc/libs/1_37_0/doc/html/boost/algorithm/is_not_greate… Documentation states "Compare two operands using > operator", when implementation use <= operator. Best regards, Anders Dalvander

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rule python-extension unknown in module Jamfile
by Patrick Meier 29 Nov '08

29 Nov '08

Hello, I am trying to get started with boost.python. When following the tutorial http://www.boost.org/doc/libs/1_37_0/libs/python/doc/tutorial/doc/html/pyth… I get the same problems that have been described in https://bugs.launchpad.net/ubuntu/+source/boost/+bug/164551, namely: $ bjam --toolset=gcc test Jamroot:18: in modules.load rule python-extension unknown in module Jamfile</usr/share/doc/libboost-doc/examples/libs/python/example>. /usr/share/boost-build/build/project.jam:312: in load-jamfile /usr/share/boost-build/build/project.jam:68: in load /usr/share/boost-build/build/project.jam:170: in project.find /usr/share/boost-build/build-system.jam:248: in load /usr/share/boost-build/kernel/modules.jam:261: in import /usr/share/boost-build/kernel/bootstrap.jam:132: in boost-build /usr/share/doc/libboost-doc/examples/libs/python/example/boost-build.jam:7: in module scope $ This may be an Ubuntu problem, but there was no reaction on the bug report since one year. Can you suggest a solution or explain how to find the cause of the problems? (I am running Ubuntu 8.10 and have installed the packages (among others) libboost-python-dev libboost-python1.34.1 boost-build libboost-doc bjam) Thank you Patrick

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Intersection Points in Higher Dimension
by Chaman Singh Verma 28 Nov '08

28 Nov '08

Hello, How can I know the intersection points of the polytope defined by a_1 x_1 + a_2 x_2 + ........................................ a_n x_n = b_1 . . . where n is very large number. Besides knowing the corner vertices of the polytope, I am interested in knowing the (n-2), (n-1) simplices. Please let me know if they can be done using CGAL. Thanks, csv Poona, India

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ignoring stuff
by jono 28 Nov '08

28 Nov '08

hi all, i'm trying to ignore unecognized lines of input (so following lines can be processed without the parse failing). eg: very simple scenario as follows: ///=================================================== { using namespace boost::spirit; typedef file_iterator<char> iterator_t; typedef scanner<iterator_t, scanner_policies_t> scanner_t; typedef rule<scanner_t> rule_t; int red=0, green=0, blue=0; rule_t option = (str_p("red") >> '=' >> int_p[assign(red)]) | (str_p("green") >> '=' >> int_p[assign(green)]) | (str_p("blue") >> '=' >> int_p[assign(blue)]) | ; iterator_t first(filename.c_str()); if (!first) return; iterator_t last = first.make_end(); parse(first, last, *option, space_p); } ///=================================================== wiw is a parser that will skip over the unrecognized line with input like this: ------------------ red = 255 kermit = green green = 128 blue = 128 ------------------ and correctly interpret the green and blue values.. i played around with eol_p as i want to skip whole lines of unrecognized content. i thought it would be easy, but i can't seem to get it right. can anybody do my job for me? cheers Jono

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[graph] property_map from bundled properties in a subgraph, how?
by Christian Rössel 28 Nov '08

28 Nov '08

Hi, thanks for the great graph library! My first attempts with boost.graph were quite successful, but now I'm stuck. My question is: How can I get a property_map from bundled properties in a subgraph? (boost 1.34.1, g++ and VC8) In the beginning I had a bidirectional graph with bundled properties and I used a property map from the edge's bundled properties: #include <boost/graph/adjacency_list.hpp> #include <boost/graph/subgraph.hpp> using namespace boost; struct VertexProperty { // ... }; struct EdgeProperty { double length_; // ... }; typedef adjacency_list<vecS, vecS, bidirectionalS, VertexProperty, EdgeProperty> Graph; int main () { Graph g; typedef property_map<Graph, double EdgeProperty::*>::type EdgeWeightMap; EdgeWeightMap ewm = get (&EdgeProperty::length_, g); // use ewm in an algorithm ... return 0; } Everthing worked fine. Then, I had to change the graph-type from adjacency_list to subgraph ... typedef subgraph< adjacency_list<vecS, vecS, bidirectionalS, property<vertex_index_t, int, VertexProperty>, property<edge_index_t, int, EdgeProperty> > > Subgraph; int main () { Subgraph g; typedef property_map<Subgraph, double EdgeProperty::*>::type EdgeWeightMap; EdgeWeightMap ewm = get (&EdgeProperty::length_, g); // use ewm in an algorithm ... return 0; } ... and got this compile error: In instantiation of `boost::property_map<Subgraph, double EdgeProperty::*>': subgraph_property_map.cpp:45: instantiated from here ../../vendor/boost_1_34_1-multithread/boost/graph/properties.hpp:355: error: no type named `vertex_bundled' in `class Subgraph' ../../vendor/boost_1_34_1-multithread/boost/graph/properties.hpp:356: error: no type named `edge_bundled' in `class Subgraph' ../../vendor/boost_1_34_1-multithread/boost/graph/properties.hpp:360: error: no type named `vertex_bundled' in `class Subgraph' ../../vendor/boost_1_34_1-multithread/boost/graph/properties.hpp:360: error: `value' is not a member of `<declaration error>' ../../vendor/boost_1_34_1-multithread/boost/graph/properties.hpp:364: error: no type named `vertex_bundled' in `class Subgraph' ../../vendor/boost_1_34_1-multithread/boost/graph/properties.hpp:364: error: `value' is not a member of `<declaration error>' ../../vendor/boost_1_34_1-multithread/boost/graph/properties.hpp:367: error: no type named `vertex_bundled' in `class Subgraph' ../../vendor/boost_1_34_1-multithread/boost/graph/properties.hpp:367: error: `value' is not a member of `<declaration error>' ../../vendor/boost_1_34_1-multithread/boost/graph/properties.hpp:369: error: no type named `vertex_bundled' in `class Subgraph' ../../vendor/boost_1_34_1-multithread/boost/graph/properties.hpp:369: error: `value' is not a member of `<declaration error>' Is there a way to use property maps from bundled properties in a subgraph? If not, can you give me a hint for a workaround, please. Thanks and best regards, Christian __

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Problem with MSVS 2008 with gregorian
by Dan Smithers 28 Nov '08

28 Nov '08

Hi I have a problem building under studio 2008. It appears that #define max(a,b) ... collides with the member function greg_month::max() and won't compile complaining that not enough arguments are provided. I have stripped the code down test.cpp #include <windows.h> //#undef max #include "boost/date_time/gregorian/gregorian.hpp" void foo() { boost::gregorian::greg_month::max(); } If I put #undef max before including gregorian.h then it compiles. Without I get the errors warning C4003: not enough actual parameters for macro 'max' error C2589: '(' illegal token on right side of '::' error C2143: syntax error : missing ';' before '::' Has anyone seen this before? Is there a workaround? I have tried this with boost 1.37.0 and it still causes problems. thanks dan

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[boost::iostreams] How to get number of bytes written?
by Milan Svoboda 28 Nov '08

28 Nov '08

Hi All, I'm using boost::iostreams and its filters to compress and decompress data. However I'm not able to retrieve number of bytes really written (number of bytes after a compression). Does anybody know how to do that? I'm currently using following code: coffset if offset to where start with writing of compressed data and after call it shall contain the length of the file. This works good to get length of the compressed block unless block of data is written somewhere in the middle of the file thus end of file is not the same as the last offset where compressed data has been written to. io::file_descriptor file(fd); file.seek(coffset, ios_base::beg); { io::filtering_ostream out; // Push the compression filter (bl->type.push(out);) out.push(file); io::write(out, buf, length); // Destroying the object 'out' causes all filters to // flush. } // Update raw length of the file. // coffset = file.seek(0, ios_base::end); Thank you for any help, Milan Svoboda

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Re: [Boost-users] [boost::iostreams] How to get number of bytes written?
by Milan Svoboda 28 Nov '08

28 Nov '08

eg wrote: > Milan Svoboda wrote: >> Hi All, >> >> I'm using boost::iostreams and its filters to compress and decompress >> data. However I'm not able to retrieve number of bytes really written >> (number of bytes after a compression). >> >> Does anybody know how to do that? >> >> I'm currently using following code: >> >> coffset if offset to where start with writing of compressed data and >> after call it shall contain the length of the file. This works good to >> get length of the compressed block unless block of data is written >> somewhere in the middle of the file thus end of file is not the same as >> the last offset where compressed data has been written to. >> >> io::file_descriptor file(fd); >> file.seek(coffset, ios_base::beg); >> { >> io::filtering_ostream out; >> // Push the compression filter (bl->type.push(out);) >> out.push(file); >> >> io::write(out, buf, length); >> >> // Destroying the object 'out' causes all filters to >> // flush. >> } >> // Update raw length of the file. >> // >> coffset = file.seek(0, ios_base::end); >> > > Maybe I dont quite understand the problem... I need to know number of bytes after compression. boost::iostreams::write returns number of bytes that has been passed to filter but there is no direct way to get number of bytes that filter returned... > Could you just write a simple pass-through filter which counts the bytes > only? Something like: > > io::filtering_ostream out; > out.push(compressor()); > out.push(passthru()); // <- this just counts bytes > out.push(file_sink("my_file.txt")); Great! This looks like a right way. Thank you! Milan

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boost and std::wstring
by Sean Farrow 28 Nov '08

28 Nov '08

Hi: Does boost work with std::wstring? Also is there a way to tell c++ to use std::wstring when instanciating an std::string? Cheers Sean.

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Turn off the Header
by Dinesh Kumar R 27 Nov '08

27 Nov '08

Hi Guyz, > *Can you please tell me how to turn off the following in Boost > Serailization? I dont need the following in my document.* > <!DOCTYPE boost_serialization> > <boost_serialization signature="serialization::archive" version="3"> > > *How do I Serialize an array of Object?* > > eg: > class simulated_defects > { > friend class boost::serialization::access; > // friend std::ostream & operator<<(std::ostream &os, const > simulated_defects &gp); > > public: > int defect_num[10]; > int defect_pos; > int defect_area; > float defect_type; > > template<class Archive> > void serialize(Archive & ar, const unsigned int /* file_version */){ > ar & BOOST_SERIALIZATION_NVP(defect_num) > & BOOST_SERIALIZATION_NVP(defect_pos) > & BOOST_SERIALIZATION_NVP(defect_area) > & BOOST_SERIALIZATION_NVP(defect_type); > } > }; > > simulated_defects object[10]; to serialize array of object , I need a > wrapper to define this object inside a class and then serailize, is there > any straight forward method? If i use loop to serialize the Headers at the > top of xml file is inserted at start of each loop? > > Can u please help me? > > > Herzliche Grüße, > Dinesh Kumar > Allmandring 18 A 06 > 70569 Stuttgart > Mobile:+4917682140240 >

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