October 2011 - Boost-users - lists.preview.boost.org

[regex] /g
by Andrey Moshbear 25 Oct '11

25 Oct '11

I have a few questions regarding implementing /g when using boost.regex. Firstly, is the iterator-pair form of match equivalent to /g? I.e. { sregex_iterator m1(str.begin(), str.end(), regex); sregex_iterator m2; for (; m1 != m2; ++m1) { // do something with *m1 } } Secondly, does regex_replace() loop internally in a /g fashion? 001100 Andrey "m05hbear" Vul 010010 011110 andrey at moshbear dot net 100001 andrey dot vul at gmail 101101 110011

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[fusion] push_back / pop_back
by Daniel Bradburn 25 Oct '11

25 Oct '11

Hi, I am trying to do the following: #include <string>#include <boost/fusion/tuple.hpp>#include <boost/fusion/include/push_back.hpp>#include <boost/fusion/include/pop_back.hpp> int main(int argc, char* argv[]) { typedef boost::fusion::tuple<int> T1; typedef boost::fusion::result_of::push_back<const T1, std::string>::type T2; T1 a(0); T2 b(boost::fusion::push_back(a, std::string(""))); boost::fusion::get<0>(); T1 c(boost::fusion::pop_back(b)); return 0; } However I get the following compilation errors: error C4430: missing type specifier - int assumed. Note: C++ does not support default-int error C2868: 'boost::lazy_disable_if_c<B,T>::type' : illegal syntax for using-declaration; expected qualified-name error C2602: 'boost::lazy_disable_if_c<B,T>::type' is not a member of a base class of 'boost::lazy_disable_if_c<B,T>' error C2504: 'boost::fusion::extension::at_impl<Tag>::apply<Sequence,N>' : base class undefined error C2504: 'boost::fusion::extension::at_impl<Tag>::apply<Sequence,N>' : base class undefined error C2146: syntax error : missing ';' before identifier 'type' error C2039: 'type' : is not a member of 'boost::fusion::result_of::at_c<Sequence,N>' error C2664: 'boost::fusion::tuple<T0>::tuple(const boost::fusion::tuple<T0> &)' : cannot convert parameter 1 from 'boost::fusion::iterator_range' to 'const boost::fusion::tuple<T0> &' error C2146: syntax error : missing ',' before identifier 'type' error C2065: 'type' : undeclared identifier error C2039: 'type' : is not a member of 'boost::fusion::result_of::prior<Iterator>' Having read the topic here : http://lists.boost.org/Archives/boost/2011/08/184624.php it looks like this is partly due to a bug in the pop_back implementation. Is there a fix for this? However I would like to know if it is also possible to use boost::fusion::get on the result of push_back? Best regards Daniel Bradburn

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throw and catch exception
by Christer Borgqvist 25 Oct '11

25 Oct '11

I have a code like this when execute the IdHTTPServDataEMVObj.Exequte(); it will throw a std::runtime_error if running one thread all is fine, the catch is excequted, but if running two threads then the application crash. What is the problem, have i miss something appreciate any help. huvcbo.. void server(boost::asio::io_service& io_service, short port) { tcp::acceptor a(io_service, tcp::endpoint(tcp::v4(), port)); for (;;) { socket_ptr sock(new tcp::socket(io_service)); a.accept(*sock); boost::thread t(boost::bind(socketclientEMVthread, sock, logFunc, mygetFunc, mybackFunc, statusUpdateFunc)); } } the client thread void socketclientEMVthread( socket_ptr sock) { cout << "connect on port " << sock->remote_endpoint().port() << endl; for (;;) { char data[max_length]; boost::system::error_code error; size_t length = sock->read_some(boost::asio::buffer(data), error); if (error == boost::asio::error::eof) break; // Connection closed cleanly by peer. else if (error) throw boost::system::system_error(error); // Some other error. std::string trans_in(data), trans_out; CIdHTTPServDataEMVObj IdHTTPServDataEMVObj(trans_in); try { // this is thrown IdHTTPServDataEMVObj.Exequte(); if ( IdHTTPServDataEMVObj.txBufferlen > 0 && IdHTTPServDataEMVObj.txBufferlen != std::string::npos) { trans_out = IdHTTPServDataEMVObj.txBuffer; } else { trans_out = trans_in; } } catch(trans_error &te) { trans_out = te.what(); boost::asio::write(*sock, boost::asio::buffer(trans_out, trans_out.size())); break; } boost::asio::write(*sock, boost::asio::buffer(trans_out, trans_out.size())); break; } }

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[date time] How to get "10" and not "Oct"
by Ken Murphy 24 Oct '11

24 Oct '11

I have the following code: std::string db_time() { typedef boost::posix_time::ptime TimeT; TimeT ct = boost::posix_time::microsec_clock::local_time(); std::stringstream ss; boost::local_time::local_time_facet* output_facet = new boost::local_time::local_time_facet("%Y-%m-%d %h:%m:%s"); ss.imbue(std::locale(std::locale::classic(), output_facet)); ss << ct; return ss.str(); } Currently, the following string is returned: 2011-Oct-24 12:43:05.476990 How do I get the month as "10" and not as "Oct"? Ken Murphy

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asio. documentation errors.
by niXman 24 Oct '11

24 Oct '11

Hi list! In the documentation for upd::socket::bind(): http://www.boost.org/doc/libs/1_47_0/doc/html/boost_asio/reference/basic_da… examples are shown from the tcp::socket::bind() Thanks. niXman.

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Problems with (de)serialization from/through pointer to base class
by Rafael Arco Arredondo 24 Oct '11

24 Oct '11

Hello: I am encountering problems with boost::serialization, particularly when objects are sent with boost::mpi and contain pointers to a base class. I am getting segmentation faults, but not always, only when the transmitted objects exceed a particular size. I have two abstract classes, A and B, two instantiable classes, D and E, and a fifth class C, which is the class eventually serialized and contains one pointer to an object of class A and another to an object of class B. In the example attached, when n (which determines the size of E objects) is 1000, everything works fine. If, for instance, n=2000, the segmentation fault appears when the object is deserialized after calling comm.recv. The output for this last case is also attached in file output.log. I am also using boost::shared_ptr as well to wrap class C objects, but the error is also thrown when no shared pointers are used. When types and object sizes are known a priori there are no problems, but I would need something more general and dynamic right now. It is possible to do this, isn't it? Any ideas of what is happening? Am I doing something wrong? Did I miss something in the documentation? Is there any size limitation for serializing/deserializing objects? I imagine MPI_Unpack, which appears in the stack trace, is restricted by the size of the input buffer, indicated by an int, but I believe this is not the problem here. Is it perhaps a bug? Any help or comments will be appreciated. Thank you in advance, Rafa

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[optional] Working around gcc 4.6 bug which produces error "‘*((void*)& aNewItem +8)’ may be used uninitialized in this function"
by Rob Desbois 24 Oct '11

24 Oct '11

I've just begun having issues with some use of boost::optional producing the error shown in the subject. This is a gcc bug, filed at http://gcc.gnu.org/bugzilla/show_bug.cgi?id=47679 The corresponding downstream bug for RedHat/Fedora is at https://bugzilla.redhat.com/show_bug.cgi?id=676361 and has a code listing to reproduce. Sending this partially as an FYI, and also to ask if anyone has any workaround? Altering client code to construct with boost::none or a false condition, then assigning a value if required, still yields the error on the assign operation. My current workaround is to initialize the optional<T> in question with a dummy T instance, then call reset() with no params if I want an 'uninitialized' optional. It looks rather bizarre, but if it must be then it must be. -- Rob Desbois Eml: rob.desbois(a)gmail.com Blog: http://theotherbranch.wordpress.com/

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[regex] Grouping behaviour
by U.Mutlu 24 Oct '11

24 Oct '11

Hi, I need to split a regex pattern into two groups like from this blafoo to (bla)(foo) But the second variant matches also input like this one: blaABCfoo There is no .* between the groups, so I wonder why it still matches. How to fix this?

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Re: [Boost-users] [locale] IOStream encoding conversions?
by Artyom Beilis 24 Oct '11

24 Oct '11

> Currently I'm messing about with Boost.Locale, I'm intending to use it > for my project, but I don't know how to do something along the lines of > specifying the external encoding (usually the user's locale, en_US.UTF-8 > in my case), and the internal coding of my program (UTF-16), > to have input and output converted, possibly using a codecvt. A possible example > would be translating UTF-16-≥POSIX UTF-8 paths, or UTF-8-≥Windows UTF-16 > paths. I assume you use Windows and wide characters. It is enough to imbue the locale to the output **wide** stream and write to it. boost::locale::generator gen; // stdout std::wcout.imbue(gen("")); std::wcout << L"שלום" << std::endl; // UTF-8 file I/O std::wfstream stream; stream.imbue(gen("")); stream.open(name,std::wfstream::out); stream << L"שלום" << std::endl; Would actually output the text in narrow encoding. Also there is an example how to create custom wide streams that would convert wide to narrow encoding http://svn.boost.org/svn/boost/trunk/libs/locale/doc/html/charset_handling.… Also for converting things like path UTF-8/UTF-16 you can use utf_to_utf functions that work just on chunks of text. http://svn.boost.org/svn/boost/trunk/libs/locale/doc/html/group__codepage.h… Artyom Beilis -------------- CppCMS - C++ Web Framework: http://cppcms.sf.net/ CppDB - C++ SQL Connectivity: http://cppcms.sf.net/sql/cppdb/

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Portable stack trace mechanism?
by Chris Cleeland 24 Oct '11

24 Oct '11

I've written this code several times and thought boost might have something. No, it doesn't, but I found this old bit thread: http://lists.boost.org/Archives/boost/2010/10/172303.php >From the evidence I can conclude that it never made it in, but the thread gives no indication as to why. I don't want to resurrect something that's already been fully hashed and excluded, but if it never made it in simply because nobody carried the torch forward, perhaps I could be the new bearer.

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