April 2007 - Boost-users - lists.preview.boost.org

Re: [Boost-users] store vector<> to filesystem (newbie question)
by Gennady Khokhorin 18 Apr '07

18 Apr '07

>template<typename Archive> >struct Serializer { > static void save(const vector<double>& timeStamps) { > std::ofstream ofs("file.bin", std::ios::binary); > > Archive oa(ofs); > oa << timeStamps; > } >}; > >Serializer<binary_oarchive>::save(timeStamps); Thanks, Bill, for your fast respond! Started reading serialization. Did try to use serialization from your sample, got stuck with error message: Error 20 error C2039: 'serialize' : is not a member of 'std::vector<_Ty>' c:\boost\include\boost-1_33_1\boost\serialization\access.hpp 109 Is it restriction sign for using std::vector<> with << operator or I'm missing some headers? my settings: #include <boost\archive\binary_oarchive.hpp> using namespace boost::archive; gok

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filesystem path initialization question...
by Graham Reitz 18 Apr '07

18 Apr '07

Why does the following path initialization throw this? "boost::filesystem::path: invalid name "c:" in path: "c:/dev/Sandbox/file_system/ textfile1.txt" How do you set paths that should work on windows and linux without avoiding this issue? Since linux doesn't have drive like C: D: and etc? try { // Is this not an appropriate method to initialize path objects? path text_file(current_path().string() + "/textfile1.txt"); if (exists(text_file)) { cout << file_size(text_file) << endl; } } catch (const filesystem_error& e) { cout << e.what() << endl; } I am running this under windows. Thanks, Graham

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[Pool][singleton_pool] Performance problem or bad usage?
by Aubrey, Jason 18 Apr '07

18 Apr '07

Hi, I've created a helper class called MemoryPooled to help add pooling to some of my classes; however, the performance seems slow by comparison to non-pooled behavior. My code is shown below, I suspect I'm doing something wrong but I don't see how it can be my class. Does anyone have any idea? -Jason // Begin code -------------------------------------- #include <Utilities/stopwatch.h> #include <boost/pool/singleton_pool.hpp> #include <boost/shared_ptr.hpp> #include <iostream> template<typename T> class MemoryPooled : public T { public: MemoryPooled(){} virtual ~MemoryPooled(){} static const int countObjectsInitiallyAllocated = 1000; typedef boost::singleton_pool<T, countObjectsInitiallyAllocated> Pool; void* operator new(size_t /*p_memSize*/) { return Pool::malloc(); } void operator delete(void* p_memBlock) { Pool::free(p_memBlock); } }; struct Test1 { int i0; int i1; int i2; int i3; int i4; int i5; int i6; int i7; int i8; int i9; }; void test(bool p_isPooled) { Utilities::StopWatch sw; // Stopwatch is my helper for getting times sw.start(); for(int i=0; i < 100000; ++i) { if( p_isPooled ) boost::shared_ptr<Test1> item(new MemoryPooled<Test1>()); else boost::shared_ptr<Test1> item(new Test1()); } const double elapsed = sw.elapsedTime(); cout << "Elapsed time: " << elapsed << " ms" << endl; } int main(int, char**) { test(true); test(false); } // End code -------------------------------------- Output: Elapsed time: 106.812 ms (Pooled) Elapsed time: 94.2158 ms (Not Pooled)

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karta orkanen
by Johan Råde 18 Apr '07

18 Apr '07

Här är en länk till en karta som visar vart vi ska. Orkanen är byggnad nr 1 på kartan. --Johan http://www.mah.se/upload/6744/malmokarta_sv.pdf

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store vector<> to filesystem (newbie question)
by Gennady Khokhorin 18 Apr '07

18 Apr '07

I have vector<double> timeStamps; How to store this vector to outside binary file in boost style? I'm trying to utilyze mapped file: std::vector<double> timeStamps; std::string filePath("c:\\double_test.bin"); boost::intmax_t thisFileSize(maxSize); // max good value: 0x2FFFFFFF ios::filtering_ostream out; ios::file_sink fsink(filePath); out.push(fsink); //out.write(time_stamps.begin(), thisFileSize); // out.flush(); fsink.close();

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fixing graph labels
by Harry Waye 17 Apr '07

17 Apr '07

Hello, Have created a graph using erdos_renyi_generator and the vertices are labelled 1 to n. When I remove a vertex the labels are then 1 to n-1. Is there any way to stop this relabelling from happening? Heres some info: typedef adjacency_list<setS, vecS, undirectedS> Graph; typedef erdos_renyi_iterator<minstd_rand, Graph> ERGen; Graph g(ERGen(gen, n, p), ERGen(), n); Cheers, Harry

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Thread safety and weak_ptr questions
by Dizzy 17 Apr '07

17 Apr '07

Hello struct A {} // executes before spawning any boost threads shared_ptr<A> sp(new A()); weak_ptr<A> wp(sp); // then in thread1 sp.reset(); // in thread thread2 shared_ptr<A> sp2(wp.lock()); Is the above code thread safe ? Is sp2 always either a default initilized shared_ptr<A> or a valid shared_ptr to the instance of A initially referenced by sp ? I couldn't find documentation on weak_ptr thread safety issues just on shared_ptr. I am unable to determine from the documentation what is the intended behaivour for the above code. I could look into the boost code and/or test it but I want to know not how it works but how it's intended to work (portably and all) :) Thank you. -- Mihai RUSU Email: dizzy(a)roedu.net GPG : http://dizzy.roedu.net/dizzy-gpg.txt WWW: http://dizzy.roedu.net "Linux is obsolete" -- AST

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Re: [Boost-users] Boost Regex in a DLL
by Metasebia Moges 17 Apr '07

17 Apr '07

Dear Sir, First of all, thank you for your reply. Your replies for my requests were very helpful. >You can use Boost.Regex in a dll by defining BOOST_REGEX_DYN_LINK when >building your dll, but as long as the regex code is isolated to your dll and >doesn't spill over into it's public interface then this shouldn't be >necessary. Other than that it's hard to say what the issue might be without >seeing your code. As you said, the regex code is isolated in my dll and doesn't spill over into the public interface. Then the problem could be with my code below. Would you please inspect and correct me if I am wrong somewhere? I read a phrase from a file and search for words preceded by "W=" and if the word is different from !NULL, sil, and SIL, I store them in a list called PhraseList for further processing. boost::regex re("W=\\w+"); boost::regex sre("!NULL|sil|SIL"); string s, sbuf; string::const_iterator begin, end; size_t length; sbuf = phrase; begin = sbuf.begin(); end = sbuf.end(); boost::match_results<std::string::const_iterator>matches; boost::match_flag_type flags = boost::match_default; while(boost::regex_search(begin, end, matches, re, flags)) { if(boost::regex_search(phrase, re)) { s= matches.str(); length=matches.str().size(); string item =s.substr(2,length-1); if(boost::regex_match(item,sre)) break; else{ phraseList.addString (item.c_str()); break; }//else } //if }//while I have the following code which does the job without any problem at the expense of "not using boost". I have a line read from a file: // Parse the line len=strlen(phrase); //If the phrase is a content bearing term, put it into phrase list while(i<len){ if(phrase[i] != 'W') i++; else{ i=i+2; item=&phrase[i]; if (strncmp (item,"!NULL ",6) == 0|| strncmp(item,"sil ",4)==0 || strncmp(item,"SIL ",4)==0) break; else { memcpy(phrase, item, strlen(item)+1); phraseList.addString (phrase); break; } } } I don't like the second option in spite of the fact that it works. Moreover, I want to use boost.regex for other complex tasks and I want to test it with this simple real life problem. Your input is highly appreciated! Thank you in advance! Best regards, mmoges _______________________________________________ Boost-users mailing list Boost-users(a)lists.boost.org http://lists.boost.org/mailman/listinfo.cgi/boost-users __________________________________________________ Do You Yahoo!? Tired of spam? Yahoo! Mail has the best spam protection around http://mail.yahoo.com

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regex_iterator with for_each question...
by Graham Reitz 17 Apr '07

17 Apr '07

I thought that for_each() goes while (it != end). How does for_each() 'know' what end is here? It doesn't seem to be initialized to anything. Thanks much, Graham class regex_callback { int m_sum; public: regex_callback() : m_sum(0) {} template <typename T> void operator()(const T& what) { m_sum += boost::lexical_cast<int>(what[1].str().c_str()); } int sum() const { return m_sum; } }; int main() { boost::regex("(\\d+),?"); string s = "1,1,2,3,5,8,13,21"; boost::sregex_iterator it(s.begin(), s.end(), reg); // Is end initialized to anything here? boost::sregex_iterator end; regex_callback c; // How is end valid here? int sum = for_each(it, end, c).sum(); return 0; }

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[Serialization] Closing tag in XML description missing
by Ruediger Berlich 17 Apr '07

17 Apr '07

Hi there, I've got the problem that the XML description of my serialized classes seem to be missing the final closing tag. Funnily enough loading of the XML descriptions nevertheless works. The platform is OpenSUSE 10.2, g++ 4.1.2, Boost 1.33.1 . I'll try to illustrate the problem with a small program. Output further below. /************************************************************************/ // headers + namespace statements removed to save space class test { friend class boost::serialization::access; template<class Archive> void serialize(Archive & ar, const unsigned int version){ using boost::serialization::make_nvp; ar & make_nvp("x",x); } int x; public: test(int i){ x = i; } void printX(void){ cout << "x = " << x << endl; } }; main() { test Test(1); // I want a stringstream, as my applicion is in remote processing ostringstream oss; assert(oss.good()); boost::archive::xml_oarchive oa(oss); oa << BOOST_SERIALIZATION_NVP(Test); // Closing tag is missing in output, see below cout << oss.str() << flush; // But the file has the correct content, see below ofstream ofs("print.xml"); assert(ofs.good()); boost::archive::xml_oarchive oa2(ofs); oa2 << BOOST_SERIALIZATION_NVP(Test); // Try to load the incorrect XML description works !?!?? test Test2(2); istringstream iss(oss.str()); assert(iss.good()); boost::archive::xml_iarchive ia(iss); ia >> BOOST_SERIALIZATION_NVP(Test2); // Funnily enough this seems to work Test2.printX(); // correctly prints "x = 1", not "x = 2" } /************************************************************************/ So when I give the xml_oarchive an ostringstream as argument (because my application is in remote processing and I don't need file output), the result is: /************************************************************************/ <?xml version="1.0" encoding="UTF-8" standalone="yes" ?> <!DOCTYPE boost_serialization> <boost_serialization signature="serialization::archive" version="3"> <Test class_id="0" tracking_level="0" version="0"> <x>1</x> </Test> /************************************************************************/ So here the closing tag </boost_serialization> is missing. If I do the same with an ofstream (see program) the file content is o.k. . /************************************************************************/ <?xml version="1.0" encoding="UTF-8" standalone="yes" ?> <!DOCTYPE boost_serialization> <boost_serialization signature="serialization::archive" version="3"> <Test class_id="0" tracking_level="0" version="0"> <x>1</x> </Test> </boost_serialization> /************************************************************************/ Funnily enough my problem with the ostringstream does not seem to have an influence on the loading of the XML description. What am I doing wrong ? Thanks and Best Regards, Ruediger

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