September 2010 - Boost-users

[multi-array] Extracting dimension information from a multi-array
by Ryan McConnehey 15 Jul '11

15 Jul '11

4 7

Asio unhandled exception
by Łukasz Majewski 20 May '11

20 May '11

Hello, I created a server single thread async (linux) and clinet (win). Every time client is close while server is writing to the socket connected to this client exception appears: terminate called after throwing an instance of 'boost::exception_detail::clone_impl<boost::exception_detail::error_info_injector<boost::system::system_error>>' what(): Transport endpoint is not connected Aborted and server is terminated. I dont know why this exception is unhandled. int main( int argc, char** argv ) { try { boost::asio::io_service io_service; quotation_server server( io_service ); while ( true ) { try { io_service.run(); } catch( ... ){} } } catch ( std::exception& e ) { LOG << e.what() << std::endl; } catch( ... ) { LOG << "Unexpected exception" << std::endl; } return 0; }

2 1

vs 2010 can't find correct boost lib version?
by Li, Tieniu 30 Mar '11

30 Mar '11

I built boost with visual studio 2010. Libraries of *-vc100-* are generated correctly. When trying to using boost.thread, VS 2010 generated error message: can't find *-vc90-*.lib. Any idea and fixing? Thanks a lot.

4 4

[BGL] Separating twin vertices
by Shaun Jackman 19 Mar '11

19 Mar '11

Hi, I have a directed graph where every vertex has a twin vertex. It is known ahead of time which pairs of vertices are twins. I want to remove as few vertices as possible from the graph such that no vertex and its twin is in the same connected component. Could someone suggest an appropriate algorithm? I've just started delving into the BGL. So far I'm suitably impressed! Cheers, Shaun

2 5

Simple serial port demonstration with boost asio asynchronous I/O
by Jeff Gray 26 Jan '11

26 Jan '11

A couple of weeks ago I posted a simple asynchronous demonstration of a telnet client using boost asio TCP network code. I have changed this code to turn it into a simple serial terminal application using the serial port support in the new version of boost asio. It required no changes at all the the read or write code. I just altered the initialization to use a serial port instead of a socket. Note that this is not intended to show how a fully functional application would work. There are plenty of areas that are not handled in this code. But it shows the idea and it's easy to build on this once you've got it working. Hope this helps someone else get started... Jeff

3 2

[units] subtract_typeof_helper<> help!
by Terry Golubiewski 04 Jan '11

04 Jan '11

I'm trying to use boost::geometry and boost::units together. For some reason boost::geometry doesn't represent the difference of two points as vectors. So, I'm making my own Vector class and defining Vector = Point - Point. The sample program below doesn't compile because I need to tell the units library about the special properties of point subtraction (I think). terry #include <boost/geometry/geometry.hpp> #include <boost/units/systems/si.hpp> #include <boost/units/quantity.hpp> #include <boost/units/io.hpp> #include <iostream> #include <iomanip> using namespace std; using namespace boost; using namespace boost::geometry; using namespace boost::units; typedef point<double, 3, cs::cartesian> Point; class Vector { Point _impl; friend Vector operator-(const Point& lhs, const Point& rhs); explicit Vector(Point p) : _impl(p) { } public: Vector() : _impl(0) { } Vector(double dx, double dy, double dz=0) : _impl(dx, dy, dz) { } friend ostream& operator<<(ostream& os, const Vector& v) { return os << dsv(v._impl); } }; // Vector inline Vector operator-(const Point& lhs, const Point& rhs) { Point tmp(lhs); subtract_point(tmp, rhs); return Vector(tmp); } inline ostream& operator<<(ostream& os, const Point& pt) { return os << dsv(pt); } int main() { Point p1(1, 2, 3); Point p2(4, 5, 6); typedef quantity<si::length, Point> Position; typedef quantity<si::length, Vector> Displacement; Position start( p1 * si::meters); Position finish(p2 * si::meters); Displacement disp(finish - start); cout << "disp=" << disp << endl; return EXIT_SUCCESS; } // main

7 16

[statechart] optional<event> - warning
by Igor R 07 Dec '10

07 Dec '10

Hello, When I define optional<my_event>, I get a warning (MSVC10): warning C4291: 'void *boost::statechart::event<MostDerived>::operator new(size_t,void *)' : no matching operator delete found; memory will not be freed if initialization throws an exception In class statechart::event I see 2 overloads of operator new: void * operator new( std::size_t size ) void * operator new( std::size_t, void * p ) But only 1 operator delete: void operator delete( void * pEvent ) i.e., no placement delete. Is this intentional? Thanks.

2 4

Linker error on windows
by Lars Mogensen 22 Nov '10

22 Nov '10

Hi, I am using BOOST to do math and have not been able to get the "findroot_demo.cpp" example of root finding to work. There seem to be a reference to rint(), which is not implemented in the C++ library for windows. How can I solve this - my understanding of BOOST is that it is cross-platform? 1>------ Build started: Project: boostfindzero, Configuration: Debug Win32 ------ 1>Compiling... 1>findroot_demo.cpp 1>Linking... 1>findroot_demo.obj : error LNK2019: unresolved external symbol _rint referenced in function "public: static double __cdecl boost::numeric::interval_lib::detail::x86_rounding::to_int(double const &)" (?to_int@x86_rounding@detail@interval_lib@numeric@boost@@SANABN@Z) 1>D:\dokumenter\lvm_AM\Visual Studio 2008\Projects\boostfindzero\Debug\boostfindzero.exe : fatal error LNK1120: 1 unresolved externals 1>Build log was saved at "file://d:\dokumenter\lvm_AM\Visual Studio 2008\Projects\boostfindzero\boostfindzero\Debug\BuildLog.htm" 1>boostfindzero - 2 error(s), 0 warning(s) ========== Build: 0 succeeded, 1 failed, 0 up-to-date, 0 skipped ========== Thanks in advance. /Lars

4 8

Interest in B-tree library for Boost?
by Beman Dawes 17 Nov '10

17 Nov '10

A Boost B-tree library would provide disk-based associative containers that scale all the way from really, really, small to really, really, large. B-trees perform well on hardware ranging from ancient floppy disk drives all the way up to humongous disk arrays. They are the technology behind most high-performance disk file systems and databases. If you don't know what a B-tree is, or think that "B-tree" is an abbreviation for "Binary tree", you might want to read the Wikipedia B-Tree article: http://en.wikipedia.org/wiki/B-tree. Knuth and other computer science texts also supply descriptions. See http://mysite.verizon.net/beman/btree/index.html for a more complete description of the proposed library. A preliminary implementation is available. Download http://mysite.verizon.net/beman/btree/btree-preview-1.zip, and unpack into a current Boost distribution. A few existing Jamfiles will be overwritten. The only compilers tested and working so far are VC++ 10 and GCC/MinGW 4.5. You can view the library online at http://github.com/Beman/Boost-Btree There is no detailed documentation yet, but if you know how to use std::map and other standard library associative containers, you already know most of what you need to know. Critical differences are documented in the Library Characteristics section of the index.html page referenced above. Initial timing tests have been very encouraging. The time test compares the btree_map implementation to std::map. As expected, a btree_map is many times slower than a std::map, given a cold operating system file cache and constraining the btree_map's caching to a minimum. But at the other extreme, when the O/S file cache is warm and the btree_map's cache is as large as the file, the btree_map is very similar in speed to std::map.The btree library's code is still very new, so timings and everything else may be subject to lots of revision. Any interest? --Beman

5 11

[Program Options] Positional args in help message
by Lindley M French 10 Nov '10

10 Nov '10

The examples for how to use positional arguments are great and seem to work fine. However, I'm wondering if there's an automatic way to include that information in the help message. In particular, since the tutorial goes to the trouble of telling you how to exclude the positional options from the options help, it would be nice to know what to replace it with. I could manually write a line detailing the usage before outputting the options description, of course, but I was wondering if there was anything in PO to handle this automatically.

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