July 2003 - Boost-users - lists.preview.boost.org

boost_date_time: ftime ==>gettimeofday for microsec_clock?
by dick.bridges＠tais.com 28 Jul '03

28 Jul '03

I need a microsec_clock on Windows XP. My first impulse is to define gettimeofday() implemented using ftime(). Should this work ok or am I missing something obvious? TIA

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Newbie - stack overflow in connected components
by Frank H 28 Jul '03

28 Jul '03

Hello: Environment: Windows 2K, MSVC 6 SP5, Boost 1.30.0 I'm new to BGL ( 2 days experience ) and am trying to use the connected components graph. My implementation seems to be OK for my small test case ( 10 verticies) but when I run my "real data" through it ( 15000 verticies) I get a stack overflow error. I note that there is a patch in the sourceforge CVS for the dfs algoritm which implements a non-recursive solution from dgregor that I understand will avoid the stack overflow. I naively downloaded the "depth_first_search.hpp" V1.35 from the CVS and of course it doesn't compile. The question: "How can I apply the patch to fix the stack problem( ie how to determine what and where are the other files I need or do I download the entire current version ( ie tag MAIN)?" Thanks for any help Frank

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RE: [Boost-Users] Newbie missing a header for boost_date_time?
by dick.bridges＠tais.com 28 Jul '03

28 Jul '03

<history> <snip/> > ...which refers to lexical_cast.hpp > > template<typename Target, typename Source> > class lexical_stream > { > bool operator<<(const Source &input) > { > here ===> return stream << input; <==== here > } > } <snip/> I'm starting to think this may be related to the 1_30_0 lexical cast problem. Can you upgrade lexical_cast.hpp from cvs? You can download it from here: http://cvs.sourceforge.net/cgi- bin/viewcvs.cgi/boost/boost/boost/lexical_cast.hpp Jeff </history> I downloaded the head this (Monday) morning and replaced the 1_30_0 version. Compile error disappeared. (Sanity check: copied the 'old' version back and compile error re-appears.) Thanks for the help. That was driving me nuts.

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link problems with precompiled headers and boost libs?
by co_tangens 28 Jul '03

28 Jul '03

Hi, I'm using the datetime library of boost 1_30_0 with VC7.1 with precompiled headers on. We're getting the following link warnings/errors: om.lib(bg_extra.obj) : warning LNK4006: ___@@_PchSym_@00@UwvevolknvmgUtnkEPozhgUhlfixvUytPzwwOlyq@ already defined in om.lib(bg_init.obj); second definition ignored om.lib(bg_extra.obj) : error LNK2005: ___@@_PchSym_@00@UwvevolknvmgUtnkEPozhgUhlfixvUytPzwwOlyq@ already defined in om.lib(bg_init.obj) We include boost headers in our own header files. Our own headerfiles are then used to create a precompiled header. It seems that all object files that use the precompiled header get these link errors... Does anyone know the reason/ a solution for this error? Thanks a lot!

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spirit & tokenizer
by Andrey Sverdlichenko 28 Jul '03

28 Jul '03

Hello. Is there any "right way" to parse strings, already splitted with tokenizer? I wrote iterator that can work with this splitted strings, but i also need some "skip parser" to recognize token boundaries as whitespaces and can't design one. -- Best regards, Andrey mailto:blaze@lists.infosec.ru

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lexical_cast problem with Unicode
by Stefan Felkel 27 Jul '03

27 Jul '03

I have problems compiling the following piece of code under Microsoft Visual C++ 6.0 with UNICODE defined. The compiler complains about a missing operator<<. What can I do in order to get this programme compiled ? #include <iostream> #include <boost/lexical_cast.hpp> int main( int argc, char * argv [] ) { std::wcout << boost::lexical_cast<std::wstring>( std::wstring( L"test" ) ).c_str() << L"\n"; return 0; } c:\programme\boost_1_30_0\boost\lexical_cast.hpp(148): error C2679: binary '<<': no operator defined which takes a right-hand operand of type 'const wstring' (or there is no acceptable conversion) c:\programme\boost_1_30_0\boost\lexical_cast.hpp(146): while compiling class-template member function 'bool boost::detail::lexical_stream<wstring,wstring>::operator <<(const wstring &)' Thanks in advance, Stefan

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Announce: Advanced Los Angeles C++ Users Group
by Jon Stewart 27 Jul '03

27 Jul '03

Hi! A small group of like-minded C++ programmers in Pasadena, CA has been meeting regularly for the past few months. The group's name is ALACPP, for Advanced Los Angeles C++, and we're interested in teaching ourselves more about generic programming and other advanced C++ techniques. Obviously, we're Boost users! We read books together and have weekly lunch meetings to discuss them; we just finished _Modern C++ Design_ and are moving on to Herb Sutter's _Exceptional C++_. We're also organizing periodic evening meetings, to explore specific topics in depth. If you'd like to give a relevant presentation to the group, please contact me! If you're in the Los Angeles area, I invite you to check out the group. Our meager website can be found here: http://www.alacpp.org and you can sign up for our mailing list here: http://lists.ellipsis.cx/mailman/listinfo/alacpp Thanks! Jon -- Jon Stewart stew1(a)ellipsis.cx

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Newbie shared_ptr in a container question.
by Joshua 27 Jul '03

27 Jul '03

I've been reading through posts on here and in the docs but I think I may have missed something. Heres what I am trying to do: lets say I have a class Foo* and I'm trying to use it in a std::vector<shared_ptr<Foo> >. I can add them all day long and it works fine. The problem is that when I try to remove the shared_ptr from the vector. I expected it to delete the memory for the Foo* then delete itself (to completely free the memory that the shared_ptr used and the memory that the Foo was using. I think this is not happening though since the destructor is not being called when the elements are removed from the vector. Heres how I am currently inserting the shared_ptr's into the vector (yes I know this is the wrong way now that I've read a few of the posts here): typedef std::vector<boost::shared_ptr<Foo> > FooVector; FooVector Foobar; Foo* blah = new Foo(); boost::shared_ptr<Foo> * NewPointer = new boost::shared_ptr<Foo>(blah); Foobar.insert(*NewPointer); //Yes I know this looks horrible. And its probably wrong. When I call Foobar.erase() I thought that the shared_ptr would be removed and the memory freed (and Foo's destructor called). I tried it like this : FooVector::iterator CurrentFoo = Foobar.begin(); Foobar.erase(CurrentFoo); That did remove the shared_ptr but the Foo* did not seem to get deallocated, its destructor was never called. Some of the posts seem to indicate that this is a very bad way to let shared_ptr manager the memory, is there a better way to do what I want to do using shared_ptr or is shared_ptr the wrong tool to use?

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Building Thread Tests on Red Hat 9.0
by Paul Grenyer 26 Jul '03

26 Jul '03

Hi All I'm trying the boost threading library for the first time. I've successfully built the threading library itself and now I want to build the tests. I've followed the instructions, but the build seems to hang at this point: execute-test ../../../libs/thread/test/bin/test_once.test/gcc/debug/runtime-link-dynamic/threading-multi/test_once.run Is this normal? I've left it for a few minutes to see if I was just being impatient, but it doesn't continue. Also, I've been looking for some code examples in the documentation on the website, I seem to remember there being some when I looked at potentially using the threads on Windows about 18 months ago, but I can't find them now. Any pointers greatly appreciated. -- Regards Paul Paul Grenyer Email: pjgrenyer(a)iee.org Web: www.paulgrenyer.co.uk EvaneScence: http://www.evanescence.com

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Newbie: boost::filesystem::fstream base class undefined error
by sea2stl 25 Jul '03

25 Jul '03

I am using VC++6 SP5, STLPort 4.5.3, boost 1.30.0. I am tring to use boost::filesystem::fstream objects in conjuction with boost::filesystem::path objects. When I create an ifstream object, the compiler gives the following message: error C2504: 'basic_ifstream<char,class _STL::char_traits<char> >' : base class undefined. Above error takes me to ln 47 in fstream.hpp. Similar problem with ofstream. Any suggestions? Thanks, Aaron Laws

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