October 2007 - Boost-users - lists.boost.org

lexical_cast
by Peter Sliepenbeek 05 Oct '07

05 Oct '07

Hi all, The test below fails: #include <iostream> #include <boost/lexical_cast.hpp> int main(int argc, char* argv[]) { std::string s; try { double d = std::numeric_limits <double> ::max(); s = boost::lexical_cast <std::string> (d); } catch (const boost::bad_lexical_cast&) { std::cout << "double to std::string fails" << std::endl; } try { double dd = boost::lexical_cast <double> (s); } catch (const boost::bad_lexical_cast&) { std::cout << "std::string to double fails" << std::endl; } return 0; } To solve this issue I propose to alter the line "stream.precision(std::numeric_limits<Target>::digits10 + 1" in the constructor for lexical_stream into "stream.precision(std::numeric_limits<Target>::digits10 - 1". Regards, P. Sliepenbeek --------------------------------- Be a better Heartthrob. Get better relationship answers from someone who knows. Yahoo! Answers - Check it out.

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[Boost.FileSystem] File or Wildcards in Path? How-to do this?
by Lawrence Spector 05 Oct '07

05 Oct '07

Here's a simple example. Is there a way to do achieve this effect? std::string folderName = "C:\\*.sys"; boost::filesystem::path fsDirectoryPath = boost::filesystem::system_complete( boost::filesystem::path(folderName, boost::filesystem::native)); boost::filesystem::directory_iterator end_iter; for (boost::filesystem::directory_iterator dir_itr(fsDirectoryPath); dir_itr != end_iter; ++dir_itr) // throws exception { std::cout << "Contains the following file: " << dir_itr->string() << std::endl; } // end for When I do this, I get the following exception: boost::filesystem::basic_directory_iterator constructor I don't see any documentation for how to narrow your searches with wildcards or how to only find files that match a particular file name. Am I missing something? Obviously you can refine your search later in the loop, but that is inefficient. Please let me know. Thanks, Lawrence

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A tuple performance question
by Peng Yu 05 Oct '07

05 Oct '07

Hi, It is mentioned at http://www.boost.org/libs/tuple/doc/tuple_users_guide.html#performance that the following two ways would be different in term of performance. ////////////// void f1(int&, double&); tuple<int, double> f2(); //Then, the call #1 may be slightly faster than #2 in the code below: int i; double d; ... f1(i,d); // #1 tie(i,d) = f2(); // #2 /////////////////// What about the current commonly used compiler, such as GCC? Are #1 and #2 different in GCC? Does the compiler always have some way to optimize #2 to make it as good as #1? Is it just a matter of fact whether the optimization method is implemented? Or #2 can never be made as good as #1? Thanks, Peng

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Any way to work around missing <locale> under Windows CE ?
by luper rouch 05 Oct '07

05 Oct '07

The standard <locale> include file is not shipped with the windows CE/mobile sdks, and therefore lots of boost parts are unusable. Is there a way to work around this problem in boost ? Luper Rouch

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[interprocess]failed to build doc
by Sean Huang 05 Oct '07

05 Oct '07

Has anybody had any success in building doc for interprocess (trunk version). Doxygen 1.5.3 crashed and I switched to 1.4.7 but I'm still getting the following errors: xslt-xsltproc .\..\..\bin.v2\libs\interprocess\doc\msvc-8.0\debug\threading-multi\autodoc -xml.boostbook warning: failed to load external entity "Reference" cannot parse Reference set XML_CATALOG_FILES=..\..\..\bin.v2/boostbook_catalog.xml "xsltproc.exe" --stringparam boost.doxygen.refid " "reference"" --stringparam boost.doxygen.reftitle ""Boost.Interprocess Reference"" --xinclude -o "..\..\..\bin.v2\libs\interprocess\doc\msvc-8.0\debug\threading-multi\autodo c-xml.boostbook" "boost\boost\tools\boostbook\xsl\doxygen\doxygen2boostbook.xsl" "..\..\..\bin.v2\libs\interprocess\doc\msvc-8.0\debug\threading-multi\autodo c-xml.doxygen" ..failed xslt-xsltproc .\..\..\bin.v2\libs\interprocess\doc\msvc-8.0\debug\threading-multi\autodoc -xml.boostbook... ..skipped <p.>autodoc.xml for lack of <p..\..\..\bin.v2\libs\interprocess\doc\msvc-8.0\debug\threading-multi>autod oc-xml.boostbook... ..skipped <p..\..\..\bin.v2\libs\interprocess\doc\msvc-8.0\debug\threading-multi>inter process.docbook for lack of <p.>a utodoc.xml... ..skipped <phtml>standalone_HTML.manifest for lack of <p..\..\..\bin.v2\libs\interprocess\doc\msvc-8.0\debug\threading- multi>interprocess.docbook... ..failed updating 1 target... ..skipped 3 targets... Thanks, Sean

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Re: [Boost-users] follow up on regex questions
by Mike Marchywka 04 Oct '07

04 Oct '07

OK, I think my earlier concern about greta dropping data was incorrect as it was the result of hastily adapting a piece of code for testing- that wouldn't have occured before. I went back to verify that boost still gives the same results as greta with simpler regexes and still have identical results. Is there anything that "()" can do to the stack that could be causing flakey results? This fails on some data ( program hangs or seg faults): ATG(.)*?(TAG|TAA|TGA) >rule|2|DNA Euk ORF This works on data I have ( although I thought I saw it failing earlier, I have yet to see the 1000 other regex's fail in boost ): ATG.*?(TAG|TAA|TGA) >rule|2|DNA Euk ORF The working regex's do not have non-terminal "()"- while they may have "()" these are only at begin or end and include two choices, one of which is "^" or "|" ) My calling code looks something like this ( again, everything is char* ) while(regex_search(start, end, what, expression, flags)) { if (which>=what.size()) { es<<MM_MARK<<" which "<< which <<" vs size "<<what.size()<<'\n'; ; return -1; } int st=what[which].first - sample; int len=what[which].second-what[which].first; typedef VecTy::value_type Val; rv.push_back(Val(st,st+len )); start = what[which].second; // This makes things OVERLAP, may not be desired behavior. if ( rv.olap_group()) start = what[0].first+1; if ( rv.olap_which()) start = what[which].first+1; // update flags: flags |= boost::match_prev_avail; flags |= boost::match_not_bob; } Thanks again. >From: "John Maddock" <john(a)johnmaddock.co.uk> >Reply-To: boost-users(a)lists.boost.org >To: <boost-users(a)lists.boost.org> >Subject: Re: [Boost-users] follow up on regex questions >Date: Thu, 4 Oct 2007 17:37:22 +0100 > >Mike Marchywka wrote: > > Hi, > > Thanks for your help in the past. I would normally drop the issue at > > this point > > until I get my build environment cleaned up > > (" My build is messed up, I haven't read the documentation. What is > > wrong with YOUR library?" LOL). > > but I do have one more question which I believe is related to boost > > regex processing. > > If someone has a known good regex test program or can point to an > > obvious problem > > it may be helpful. > >You mean libs/regex/test/regress/*.cpp ? > >It would be a good idea to build and run this to verify the sanity of your >setup at least: I still have a suspision that the binaries you are using >are >not compatible with your build options or regex headers, but I can't be >sure. > > > Again, this code seems to work with Microsoft's > > greta and boost gives identical results on a longer list of SIMPLER > > regexes so I reasonably believe that the problem is due to handling > > of more complicated expression ( One caveat, to be complete, is that > > greta did seem to return some spurious > > results but they are easily filter programmatically, things like > > negative location, > > but the plausible ones that I have checked manually are right). > > However, on this sequence of regexes (regexi?) I get either an abort > > OR the program hangs > > later on non-sensical execution (I know, "Gee, you have a build > > problem and the stack is messed up?"). > > > > myboost.cpp114 (GU.*?TACTAAC.{20,40}AG|^)(.*?)(GU.*?TACTAAC.{20,40}AG) > > myboost.cpp114 ATG(...)*?(TAG|TAA|TGA) > > myboost.cpp114 TATAA.*?ATAAA > > myboost.cpp114 (GU.*?TACTAAC.{20,40}AG|^)(.*?)(GU.*?TACTAAC.{20,40}AG) > > myboost.cpp114 ATG(...)*?(TAG|TAA|TGA) > > > > ( progam hangs in my code or had been core dumping in boost::regex ) > >What is the text you are matching against? If you can give me a concrete >example I can test it here, but "it hangs" isn't very useful I'm afraid ;-) > >John. > >_______________________________________________ >Boost-users mailing list >Boost-users(a)lists.boost.org >http://lists.boost.org/mailman/listinfo.cgi/boost-users _________________________________________________________________ Help yourself to FREE treats served up daily at the Messenger Café. Stop by today! http://www.cafemessenger.com/info/info_sweetstuff2.html?ocid=TXT_TAGHM_OctH…

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[Iostreams] Issue with mapped_file
by JD 04 Oct '07

04 Oct '07

Hello, There is something I don't get with mapped_file from the IOStreams library. Here is an example: // Code snippet #include <iostream> #include <boost/iostreams/device/mapped_file.hpp> #include <boost/iostreams/stream.hpp> using namespace boost::iostreams; int main(int argc, char **argv) { if (argc != 2) return 1; try { stream <mapped_file_sink> out; mapped_file_params p(argv[1]); p.new_file_size = 1024 * sizeof (char); out.open(mapped_file_sink(p)); } catch (const std::exception &e) { std::cout << e.what() << std::endl; return 2; } return 0; } // Code snippet When compiled, the execution goes like: c:\>test_shmem somefile c:\>test_shmem somefile failed setting file size: The handle is invalid. I tried without the new_file_size, I tried with a mapped_file... Is there something I don't get? Why are we not able to open a file that already exist? Thanks for your help. JD

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[smart_ptr] shared_ptr clean-up failure
by Robbie Morrison 04 Oct '07

04 Oct '07

Hi all -- hope someone can help, many TIA -- Robbie Intro This relates to the Boost.Smart_ptr library. The example code (see below) fails when a boost::shared_ptr is used, but not when a raw pointer is substituted. This posting probably highlights some key misunderstanding on my part. Perhaps someone can explain where I went wrong. As a long shot, it could be that the Boost.Ref library can offer something useful. Problem I want to pass in an existing UDT (user-defined type) by reference to a second UDT during construction. I figured it would be better to hold this reference in a smart pointer rather than a raw pointer. The following stripped-down code mimics this process, but passes in an int (a fundamental type) instead for reasons of simplicity. The example works fine with a raw pointer, but not a boost::shared_ptr (or std::auto_ptr or boost::scoped_ptr or std::tr1::shared_ptr). I checked in Becker (2007) ("C++ standard library extensions") and Karlsson (2006) ("Beyond the C++ standard library") regarding Boost.Smart_ptr's, but could not see anything useful. 'frag-pass-by-ref_03.cc' was the name of my program. Test environment - Boost release 1.34.1 dated 24-Jul-2007 (source build) - GNU GCC 4.1.2 compiler (using -Wall -Weffc++ -pedantic) - Linux Ubuntu 6.10 operating system (now superseded by 7.04) - run-time memory checking with valgrind version "valgrind-3.2.0-Debian" - laptop is Toshiba Tecra A2 330, new 2004, 1.4GHz Intel Celeron M Error messages (normal run-time) destroying a MyClass *** glibc detected *** ./frag-pass-by-ref_03: free(): invalid pointer: 0xbfcd12dc *** ======= Backtrace: ========= /lib/tls/i686/cmov/libc.so.6[0xb7d8a8bd] /lib/tls/i686/cmov/libc.so.6(__libc_free+0x84)[0xb7d8aa44] /usr/lib/libstdc++.so.6(_ZdlPv+0x21)[0xb7f3afc1] ./frag-pass-by-ref_03(__gxx_personality_v0+0x3d3)[0x8048baf] ./frag-pass-by-ref_03[0x8048c96] ./frag-pass-by-ref_03(__gxx_personality_v0+0x274)[0x8048a50] ./frag-pass-by-ref_03(__gxx_personality_v0+0x29e)[0x8048a7a] ./frag-pass-by-ref_03(__gxx_personality_v0+0x2ba)[0x8048a96] ./frag-pass-by-ref_03[0x8048cd4] ./frag-pass-by-ref_03(__gxx_personality_v0+0x195)[0x8048971] /lib/tls/i686/cmov/libc.so.6(__libc_start_main+0xdc)[0xb7d398cc] ./frag-pass-by-ref_03(__gxx_personality_v0+0x65)[0x8048841] ======= Memory map: ======== (remainder omitted) Error messages (under valgrind) destroying a MyClass ==23254== Invalid free() / delete / delete[] ==23254== at 0x4020CC7: operator delete(void*) (vg_replace_malloc.c:244) ==23254== by 0x8048BAE: void boost::checked_delete<int>(int*) (checked_delete.hpp:34) ==23254== by 0x8048C95: boost::detail::sp_counted_impl_p<int>::dispose() (sp_counted_impl.hpp:79) ==23254== by 0x8048A4F: boost::detail::sp_counted_base::release() (sp_counted_base_gcc_x86.hpp:145) ==23254== by 0x8048A79: boost::detail::shared_count::~shared_count() (shared_count.hpp:205) ==23254== by 0x8048A95: boost::shared_ptr<int>::~shared_ptr() (shared_ptr.hpp:131) ==23254== by 0x8048CD3: MyClass::~MyClass() (frag-pass-by-ref_03.cc:21) ==23254== by 0x8048970: main (frag-pass-by-ref_03.cc:31) ==23254== Address 0xBE8944FC is on thread 1's stack (error summary omitted) 8< ------------------------------------------- #include <iostream> // standard io #include <boost/shared_ptr.hpp> // Boost shared pointer class MyClass { public: MyClass (int& i) // & indicates pass-by-reference : d_int(&i) { } // & is address-of operator ~MyClass() { std::cout << "destroying a MyClass" << std::endl; } private: boost::shared_ptr<int> d_int; // shared pointer FAILS // int* d_int; // raw pointer works }; int main() { int myint(2); // simple integer MyClass myclass(myint); // constructor call return 0; } ------------------------------------------- >8 --- Robbie Morrison PhD student -- policy-oriented energy system simulation Institute for Energy Engineering (IET) Technical University of Berlin (TU-Berlin), Germany [from IMAP client]

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boost-users: boost enable_if
by chun ping wang 04 Oct '07

04 Oct '07

template <typename T> bool boost::pseudoprime(const T& n, const T& k) { typedef boost::operators<T> operatorT; BOOST_STATIC_ASSERT(is_integral<T>::value); // static assert 1. BOOST_STATIC_ASSERT((is_base_of<operatorT, T>::value)); // static assert 2. BOOST_ASSERT (n > T(2) && n % T(2) != 0); return modular_expo(k, n-1, n) != T(1) % n ? true : false; } now in vistual studio 2005 sp1 and visual studio 2008 beta the part "is_base_of<operatorT, T>::value" does not work if T happens to be an int or long due to "error C2803: 'operator --' must have at least one formal parameter of class type". I want to use enable_if to enable the STATIC_ASSERT only if T is NOT an arithmetic type for static assert 2. How would i go about doing that?

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(no subject)
by Mark Beinker 04 Oct '07

04 Oct '07

Hi, I was trying to use the boost interval class using g++ under cygwin, but unfortunately, I have trouble to use the exp function. The following code: #include <iostream> #include <cmath> #include <boost/numeric/interval.hpp> #define DOUBLE boost::numeric::interval<double> int main(int argc, char** argv) { DOUBLE x(4,5); std::cout.precision(19); DOUBLE res = exp(x); std::cout<<'['<<res.lower()<<", "<<res.upper()<<']'<<std::endl; return 0; } generates the following compile error: /usr/include/boost/numeric/interval/transc.hpp: In function `boost::numeric::interval<T, Policies> boost::numeric::exp(const boost::numeric::interval<T, Policies>&) [with T = double, Policies = boost::numeric::interval_lib::policies<boost::numeric::interval_lib::rounded_math<double>, boost::numeric::interval_lib::checking_strict<double> >]': itest.cpp:14: instantiated from here /usr/include/boost/numeric/interval/transc.hpp:34: error: 'struct boost::numeric::interval_lib::rounded_math<double>' has no member named 'exp_down' itest.cpp:14: instantiated from here /usr/include/boost/numeric/interval/transc.hpp:34: error: 'struct boost::numeric::interval_lib::rounded_math<double>' has no member named 'exp_up' I use boost version 1.34.1. Any idea why this doesn't work? Regards, Mark

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