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[Graph] A minor bug of the max-flow algorithm?
by Da Wang 02 Aug '07

02 Aug '07

Hi there, It seems that when searching a network maxflow, if the source and sink are the same vertex, the max-flow function in BGL will create some invalid data and cause the program to crash. To reproduce, simply change the "max_flow.dat" in libs\graph\example, and change the "s" and "t" to be the same vertex. Then compile the " edmunds-karp-eg.cpp". When run "edmunds-karp-eg < max_flow.dat", Windows will give me a crash message. I am using boost 1.34.0 with MS Visual Studio Express 2005 on Win XP2. It seems that the following line 62 of edmunds_karp_max_flow.hpp is having an error: delta = min BOOST_PREVENT_MACRO_SUBSTITUTION(delta, residual_capacity[e]) I admit that generally it doesn't make sense to have the source and sink at the same vertex, but I think it will be nicer if the program can check for this simple case... Just to point this out so the author could fix it if s/he thinks it is necessary. Thanks, Da

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[regex] ".*" expression matches twice in regex_replace?
by Arne Babnik 02 Aug '07

02 Aug '07

Hi all, I am trying to perform some simple (as I thought) text manipulation. The task was to prepend a text with some other, e.g. 1234 -> 01234. I tried to do this with the expression ".*" and format "0$&". I used regex_replace with the following parameters: std::basic_string<char> string("1234"); std::basic_string<char> format("0$&"); boost::regex exp(".*"); std::basic_string<char> result; result = boost::regex_replace(string, exp, format); I was very surprised when I got the result "012340", i.e. the format string was applied twice. After some testing, I found out that regex_replace matches a second time at the end of the string, where the expression matched an empty string (therefore only the zero was appended at the end). When using the (undocumented) option match_not_initial_null, it basically works - but then empty input strings would not match either. This also applies to the expression ".+", which works correct on the input but would not match on empty strings as well. The only solution I found so far was using "^.*" as expression. Is this a bug or a feature? Or what did I get wrong with this regular expression? Regards, Arne ---------------------------------------------------------------- This message was sent using IMP, the Internet Messaging Program.

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newbie: boost::filesystem problems
by Eduard Diner 02 Aug '07

02 Aug '07

Hi, I want to use the filesystem library. For simplicity I first tried to compile the simple_ls.cpp (provided at: http://www.boost.org/libs/filesystem/doc/index.htm) Unfortunately I get lots of compiler-errors. For example the line 22: >> fs::path full_path( fs::initial_path<fs::path>() ); splitARFF.cpp:22: error: expected primary-expression before '>' token splitARFF.cpp:22: error: expected primary-expression before ')' token Does anyone have an idea how to solve the problem? THANKS The Makefile I used: ------------- OBJ = splitARFF.o CC = g++ SRC = $(OBJ:%.o=%.cpp) HDR = $(OBJ:%.o=%.h) LDFLAGS = -Wall -pg CFLAGS = -g -pg all: boostARFF boostARFF: splitARFF.o $(CC) $(LDFLAGS) $(OBJ) $(LIBS) -L/usr/lib -lboost_filesystem %.o: %.cpp $(CC) -c $(CFLAGS) $(SRC) -I/usr/include -------------

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[regex] suggestion: function object for replace
by Neil Hunt 02 Aug '07

02 Aug '07

Thanks for the excellent library John and others. I could not easily find an option to specify a callback function that somehow returns a custom built replacement string for use with regex_replace. The .NET framework utilises the MatchEvaluator mechanism: http://msdn2.microsoft.com/en-us/library/system.text.regularexpressions.reg… While there is no one definition of a string to return in the case of boost regex's, perhaps a Range or a pair of iterators would be sufficient (although temporaries may cause trouble for the unwary). Anyway, I have had need of of this mechanism and couldn't use the excellent regex_replace as a consequence. Neil

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custom allocation for boost::array
by Clemens Buchacher 01 Aug '07

01 Aug '07

Hi, Is it safe to do this? using boost::array; const size_t n; void* p = new char[sizeof(T) * n]; array<T, n>* data = new(p) array<T, n>; The reason I want to do this is that I have implemented my own memory pool, so new char[...] would be replaced by my_pool<T>::allocate(n). I don't want to use something like my_pool<array<T, n> >::allocate(1), because then my allocator would have to align the allocated memory to the total array size instead of just the size of its elements. I suppose the safest solution would be an implementation of array with dynamic memory and support for a standard allocator like, for example, a one-dimensional multi_array or even multi_array_ref? I am concerned about performance of those containers, however. Regards, Clemens

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[lambda][1.33.1] Lambda warnings after installing VS2005 SP1
by john.wismar＠autozone.com 01 Aug '07

01 Aug '07

I have just installed Service Pack 1 for VS2005, and am now getting a warning in some code using lambda::bind. There wasn't a warning previously, but I don't know if the issue is due to an update to the C++ standard library, a legitimate warning that they weren't flagging before, or a spurious warning. It looks like the issue is that I'm passing a function pointer, to bind. Is this a warning I should just ignore, or is this a legitimate issue? Thanks for your help! Here's a sample app, followed by the warnings I'm seeing. #include <boost/lambda/bind.hpp> using boost::lambda::bind; using boost::lambda::_1; #include <vector> #include <map> #include <algorithm> int main() { enum choice { select, reject }; std::vector<long> questions; std::map<long, choice> answers; std::transform(questions.begin(), questions.end(), std::inserter(answers, answers.begin()), bind(std::make_pair<long, choice>, _1, select)); return 0; } c:\boost\boost\lambda\detail\lambda_traits.hpp(389) : warning C4180: qualifier applied to function type has no meaning; ignored c:\boost\boost\lambda\detail\lambda_traits.hpp(458) : see reference to class template instantiation 'boost::lambda::detail::bind_traits<T>' being compiled with [ T=std::pair<long,main::choice> (long,main::choice) ] c:\temp\lambda_warning_test\lambda_warning_test.cpp(20) : see reference to class template instantiation 'boost::lambda::detail::bind_tuple_mapper<T0,T1,T2,T3,T4,T5,T6,T7,T8,T9>' being compiled with [ T0=std::pair<long,main::choice> (long,main::choice), T1=boost::lambda::placeholder1_type, T2=const main::choice, T3=boost::tuples::null_type, T4=boost::tuples::null_type, T5=boost::tuples::null_type, T6=boost::tuples::null_type, T7=boost::tuples::null_type, T8=boost::tuples::null_type, T9=boost::tuples::null_type ] -------------------------------- John Wismar john.wismar(a)autozone.com

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Boost.Foreach performance
by Thomas Matelich 01 Aug '07

01 Aug '07

So, I'm loving Foreach and as I watch it spread throughout our codebase, of course it runs across the desk of our optimization obsessed team member. So, I was curious if you could address runtime performance of Foreach. I would expect it to be essentially equivalent to a hand written for loop with caching of end(). But what's the overhead of the auto_any_t, etc.? Thanks, Tom

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[1.34.0 thread] vc8: "R6030 CRT not initialized" error with static executable
by Markus Werle 01 Aug '07

01 Aug '07

Hi! After some nightmare chasing a bug within my code I boiled it down to a dummy MFC MDI project including nothing else but <boost/thread/tss.hpp> the line static boost::thread_specific_ptr<void *> tld_helper; in InitInstance() triggers an "R6030 - CRT not initialized" error, but only on one single windows XP platform. The app runs fine on all others. If you have any idea what might have gone wrong, please give me a hint. I put some simplified code below. Excluding the init() line in boost::details::tss(boost::function1<void, void*>* pcleanup) removes the initializing error in the executable :-( best regards, Markus My compiler settings: Microsoft Visual Studio 2005 Version 8.0.50727.762 (SP.050727-7600) Microsoft .NET Framework Version 2.0.50727 Installed Edition: Professional [...] Microsoft Visual C++ 2005 77626-009-0000007-41492 Microsoft Visual C++ 2005 Microsoft Visual Studio 2005 Professional Edition - ENU Service Pack 1 (KB926601) Compiler flags: /Ox /Ob2 /Oi /Ot /I "D:\FEV-Data\Sourcen\cpp\VC8\Common\DLLs\boost_1_34_0" /D "WIN32" /D "_WINDOWS" /D "NDEBUG" /D "_CRT_SECURE_NO_DEPRECATE" /D "_MBCS" /FD /EHsc /MT /Yu"stdafx.h" /Fp"Release\MaximumCM_Dummy.pch" /Fo"Release\\" /Fd"Release\vc80.pdb" /W3 /nologo /c /TP /errorReport:prompt /bigobj /wd4996 Linker flags /OUT:"D:\FEV-Data\ExperimentalCode\WerleShowBug\Release\MaximumCM_Dummy.exe" /INCREMENTAL:NO /NOLOGO /LIBPATH:"d:\FEV-Data\Sourcen\cpp\VC8\Common\DLLs\boost_1_34_0\stage\lib" /MANIFEST /MANIFESTFILE:"Release\MaximumCM_Dummy.exe.intermediate.manifest" /DELAYLOAD:"OleAcc.dll" /DEBUG /PDB:"d:\FEV-Data\ExperimentalCode\WerleShowBug\release\MaximumCM_Dummy.pdb" /SUBSYSTEM:WINDOWS /OPT:REF /OPT:ICF /MACHINE:X86 /ERRORREPORT:PROMPT nafxcw.lib DelayImp.lib <snip> // WerleShowBug.cpp : Defines the class behaviors for the application. // #include "stdafx.h" #include "WerleShowBug.h" #include "MainFrm.h" #include "ChildFrm.h" #include "WerleShowBugDoc.h" #include "WerleShowBugView.h" // #include <boost/utility.hpp> #include <boost/function.hpp> #include <boost/thread/detail/config.hpp> #include <stdexcept> namespace boost { class BOOST_THREAD_DECL my_exception : public std::exception {}; namespace detail { class BOOST_THREAD_DECL tss // : private noncopyable { public: tss(boost::function1<void, void*>* pcleanup) { if (pcleanup == 0) { } try { // remove this code and it runs init(pcleanup); // } catch (...) { delete pcleanup; } } private: unsigned int m_slot; //This is a "pseudo-slot", not a native slot void init(boost::function1<void, void*>* pcleanup); }; template <typename T> struct tss_adapter { template <typename F> tss_adapter(const F& cleanup) : m_cleanup(cleanup) { } void operator()(void* p) { m_cleanup(static_cast<T*>(p)); } boost::function1<void, T*> m_cleanup; }; } // namespace detail template <typename T> class thread_specific_ptr // : private noncopyable { public: thread_specific_ptr() : m_tss(new boost::function1<void, void*>( boost::detail::tss_adapter<T>( &thread_specific_ptr<T>::cleanup))) { } thread_specific_ptr(void (*clean)(T*)) : m_tss(new boost::function1<void, void*>( boost::detail::tss_adapter<T>(clean))) { } ~thread_specific_ptr() { reset(); } T* get() const { return static_cast<T*>(m_tss.get()); } T* operator->() const { return get(); } T& operator*() const { return *get(); } T* release() { T* temp = get(); if (temp) m_tss.set(0); return temp; } void reset(T* p=0) { // T* cur = get(); // if (cur == p) return; // m_tss.set(p); // if (cur) m_tss.cleanup(cur); } private: static void cleanup(T* p) { delete p; } detail::tss m_tss; }; #ifdef BOOST_MSVC # pragma warning(pop) #endif } // namespace boost #ifdef _DEBUG #define new DEBUG_NEW #endif // CWerleShowBugApp BEGIN_MESSAGE_MAP(CWerleShowBugApp, CWinApp) ON_COMMAND(ID_APP_ABOUT, &CWerleShowBugApp::OnAppAbout) // Standard file based document commands ON_COMMAND(ID_FILE_NEW, &CWinApp::OnFileNew) ON_COMMAND(ID_FILE_OPEN, &CWinApp::OnFileOpen) // Standard print setup command ON_COMMAND(ID_FILE_PRINT_SETUP, &CWinApp::OnFilePrintSetup) END_MESSAGE_MAP() // CWerleShowBugApp construction CWerleShowBugApp::CWerleShowBugApp() { // TODO: add construction code here, // Place all significant initialization in InitInstance } // The one and only CWerleShowBugApp object CWerleShowBugApp theApp; // CWerleShowBugApp initialization BOOL CWerleShowBugApp::InitInstance() { // This one killes the app static boost::thread_specific_ptr<void *> tld_helper; // InitCommonControlsEx() is required on Windows XP if an application // manifest specifies use of ComCtl32.dll version 6 or later to enable // visual styles. Otherwise, any window creation will fail. INITCOMMONCONTROLSEX InitCtrls; InitCtrls.dwSize = sizeof(InitCtrls); // Set this to include all the common control classes you want to use // in your application. InitCtrls.dwICC = ICC_WIN95_CLASSES; InitCommonControlsEx(&InitCtrls); CWinApp::InitInstance(); // Initialize OLE libraries if (!AfxOleInit()) { AfxMessageBox(IDP_OLE_INIT_FAILED); return FALSE; } AfxEnableControlContainer(); // Standard initialization // If you are not using these features and wish to reduce the size // of your final executable, you should remove from the following // the specific initialization routines you do not need // Change the registry key under which our settings are stored // TODO: You should modify this string to be something appropriate // such as the name of your company or organization SetRegistryKey(_T("Local AppWizard-Generated Applications")); LoadStdProfileSettings(4); // Load standard INI file options (including MRU) // Register the application's document templates. Document templates // serve as the connection between documents, frame windows and views CMultiDocTemplate* pDocTemplate; pDocTemplate = new CMultiDocTemplate(IDR_WerleShowBugTYPE, RUNTIME_CLASS(CWerleShowBugDoc), RUNTIME_CLASS(CChildFrame), // custom MDI child frame RUNTIME_CLASS(CWerleShowBugView)); if (!pDocTemplate) return FALSE; AddDocTemplate(pDocTemplate); // create main MDI Frame window CMainFrame* pMainFrame = new CMainFrame; if (!pMainFrame || !pMainFrame->LoadFrame(IDR_MAINFRAME)) { delete pMainFrame; return FALSE; } m_pMainWnd = pMainFrame; // call DragAcceptFiles only if there's a suffix // In an MDI app, this should occur immediately after setting m_pMainWnd // Enable drag/drop open m_pMainWnd->DragAcceptFiles(); // Enable DDE Execute open EnableShellOpen(); RegisterShellFileTypes(TRUE); // Parse command line for standard shell commands, DDE, file open CCommandLineInfo cmdInfo; ParseCommandLine(cmdInfo); // Dispatch commands specified on the command line. Will return FALSE if // app was launched with /RegServer, /Register, /Unregserver or /Unregister. if (!ProcessShellCommand(cmdInfo)) return FALSE; // The main window has been initialized, so show and update it pMainFrame->ShowWindow(m_nCmdShow); pMainFrame->UpdateWindow(); return TRUE; } // CAboutDlg dialog used for App About class CAboutDlg : public CDialog { public: CAboutDlg(); // Dialog Data enum { IDD = IDD_ABOUTBOX }; protected: virtual void DoDataExchange(CDataExchange* pDX); // DDX/DDV support // Implementation protected: DECLARE_MESSAGE_MAP() }; CAboutDlg::CAboutDlg() : CDialog(CAboutDlg::IDD) { } void CAboutDlg::DoDataExchange(CDataExchange* pDX) { CDialog::DoDataExchange(pDX); } BEGIN_MESSAGE_MAP(CAboutDlg, CDialog) END_MESSAGE_MAP() // App command to run the dialog void CWerleShowBugApp::OnAppAbout() { CAboutDlg aboutDlg; aboutDlg.DoModal(); } // CWerleShowBugApp message handlers

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boost 1.34.1 string algorithm.
by chun ping wang 01 Aug '07

01 Aug '07

I was wondering is it really necessary to use string algorithms to find in variable str2 the last occurence that does not contain a number between 1 and 9 and create a substr base on that. regulary i would use std::string strNew = str2.substr(str2.find_last_not_of("123456789")); So 2 questions. 1.) Whats the benefit of the string algorithm version of boost in this case. 2.) How would I do this using string algorithm instead.

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newbie question
by Mike Gagnon 31 Jul '07

31 Jul '07

Hi Boost experts, I'm writing code in Visual C++ 6.0 and I'm trying to replace text in a string using a regular expression to match the text. I know there is a replace function in boost - but I don't think it's accessible from the regex++ API (or am I too much of a newbie to realize this)? Is there a way for me to use boost in Visual C++ 6.0 to do what I want? Thanks for any help! Best, Mike

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