September 2009 - Boost-users

Re: [Boost-users] lexical problem
by Anders Dalvander 15 Sep '09

15 Sep '09

pedro chaparro wrote: > in the ouput i have this : 5050?? > > the first "50" i write with > std::cout.write(buf.data(),len); > > and the second "50" plus those stange characters > > std::string datos=buf.data(); > printf("%s \n",datos); > > i suppose that those characters means that are not null terminated. right? > So how can i only take the "50" without the other characters? > > thanks > std::string does not work well with varargs, use std::string::c_str member function to convert it to a null-terminated string: printf("%s \n",datos.c_str()); Regards, Anders Dalvander

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Re: [Boost-users] lexical problem
by cliffg＠codewrangler.net 15 Sep '09

15 Sep '09

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Get results of graph cut?
by David Doria 15 Sep '09

15 Sep '09

If I do this: double flow = kolmogorov_max_flow(g, SourceNode, SinkNode); I get the value of the max flow, but how do I tell which nodes of g belong to the "source side" of the graph and which nodes belong to the "sink side"? (thinking of it as a min cut rather than a max flow problem) Also, is it possible to tell the max flow algorithm to use multiple sources/sinks? Thanks, David

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[Sigal] Combiner sample code outputs nothing
by Boost lzw 15 Sep '09

15 Sep '09

Hi there, I got nothing outputted from the following sample code on page 360 to 362 of the book "Beyond the C++ Standard". Did I missed something? Thanks in advance. Robert ============== #include <iostream> #include "boost/signals.hpp" // boost book, pp. 360 - 362 bool step0() { std::cout << "Step 0 is OK.\n"; return true; }; bool step1() { std::cout << "Step 1 is not OK. This won't do at all. \n"; return false; }; bool step2() { std::cout << "Step 2 is OK. \n"; return true; }; // we need this one as Combiner class stop_on_failure { public: typedef bool result_type; template<typename InputIterator> bool operator()(InputIterator begin, InputIterator end) const { while (begin != end); { if (!*begin) return false; ++begin; } return true; } }; int main() { boost::signal<bool (), stop_on_failure> sig; sig.connect(0, &step0); sig.connect(1, &step1); sig.connect(2, &step2); bool ok = sig(); if (ok) std::cout << "All system tests clear. \n"; else std::cout << "At least one test failed. Aborting. \n"; return 0; } ==============

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Re: [Boost-users] building boost 1_33_1 now 1_37_0
by Dan Smithers 15 Sep '09

15 Sep '09

Message: 6 Date: Tue, 15 Sep 2009 14:44:40 +0400 From: Vladimir Prus <vladimir(a)codesourcery.com> To: boost-users(a)lists.boost.org Subject: Re: [Boost-users] Boost-users Digest, Vol 2115, Issue 4 Message-ID: <h8nr6o$1od$1(a)ger.gmane.org> Content-Type: text/plain; charset=us-ascii Dan Smithers wrote: >> >> Date: Fri, 11 Sep 2009 20:06:17 +0400 >> >> From: Vladimir Prus <vladimir(a)codesourcery.com> >> >> To: boost-users(a)lists.boost.org >> >> Subject: Re: [Boost-users] building boost 1_33_1 >> >> Message-ID: <h8dshm$bce$2(a)ger.gmane.org> >> >> Content-Type: text/plain; charset=us-ascii >> >> >> >> Dan Smithers wrote: >> >> >>> >>> I need to recompile boost 1_33_1 with the intel compiler icc 9.0 >>> >>> >>> >>> The jamfiles are trying to use 8 in /opt (which doesn't actually exist). >>> >>> >>> >>> Please can someone point me in the right direction to do this. > > Thanks for the reply. > > > > I have done some more things, and decided to try the same with boost > > 1.37 - the next version that I have been using. > > >>> >>> >>> >>> I am using >>> >>> >>> >>> ./configure CXX=icc --prefix=/vol/build --with-toolset=intel-linux >>> >>> --with-bjam=/vol/build/boost-jam-3.1.17/bin.linuxx86/bjam >> >> >> >> 1.33.1 is very old; and worse, it was using older version of Boost.Build. >> >> Therefore, I'd recommend just hacking your way around in tools/build/v2/ >> >> intel-tools.jam, or however the file is called. > > > > My problem now seems to be in the actual compilation: It tries to build > > in workarounds for gcc 2.95 and complains with about wrongly named > > header files. If this results in compilation errors, you should see the compile command after the errors. > > > > Possibly the problem is because I don't understand enough Jam to work > > out what commands are actually being run. Also, the "-d+2" option will print all commands that are run, not just those that failed. Thanks for that hint - I've edited the makefile to call bjam -d+2 so I can see that it is the call to icpc that is failing. It looks as if the intel includes are not being used and the default gcc 2.95 ones are put in instead. How do I change the includes in jam?

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CentOS 4.7 and boost 1.35+
by Timothy Chan 15 Sep '09

15 Sep '09

Hi all, I have a newbie question here. I am running CentOS4.7 and have Boost 1.32 installed. I need to upgrade to at least 1.35 but it seems that yum only brings up version 1.32 or 1.33 versions. Does anybody have any recommendations on how to upgrade? If i simply download 1.40 from the website, are there any CentOS specific directions that anybody can give? Thanks for any help I can get. -Tim

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[interprocess] theoretical questions about interprocess conditions
by Kishalay Kundu 15 Sep '09

15 Sep '09

Hi, I am designing a multithreaded application that uses interprocess_condition variables as part of my synchronization process. I have some questions about the internal workings of interprocess_condition and would be grateful if someone provides their feedback on my general design. My application is designed such that there are several threads (say A, B, C & D) that all access different chunks of data asynchronously based on individual conditions (say cA, cB, cC, cD). However, each chunk needs to be accessed in sequence. So, for a single chunk of data, an example would be as following: 1. A waits on condition cA, executes its code, then issues notification for condition cB. 2. B waits on condition cB, executes its code, then issues notification for condition cC. 2. C waits on condition cC, executes its code, then issues notification for condition cD. 2. D waits on condition cD, executes its code, then issues notification for condition cA. >From the examples on the web-site, it looks like, one can use scoped_lock and interprocess_condition in the following manner: void thread_func(...) { // example code for thread B scoped_lock < boost::interprocess::interprocess_mutex > lock( my_mutex ); cB.wait( lock ); // work code // notify next thread cC.notify_all( ); } In this case, thread B will get into the my_mutex queue and wait for thread A to notify when and the condition cB is fulfilled and then take ownership of the mutex. Question 1: If thread B locks my_mutex after thread A has already issued the cB notification, will B be able to recognize this and take ownership of the mutex? My design is such that no other thread is actually waiting for cB. If B does not recognize the condition, it will result in a stall of the whole pipeline (since it won't issue notification on cC). Is this a correct assessment? Question 2: I give below an example of the code I'm using. I'd like to know if this will generate the behavior I'm looking for. The design is based on the fact that different threads perform different operations on the data and they do these operations in a particular order (eg. A, then B, then C, then D). I divide the data up into chunks so that every thread is working on some part of the data instead of being held up. I use the try_to_lock stuff so that if a thread doesn't get an immediate lock, it just moves on to the next chunk of data and sees if it can work on that. Is this an efficient way to make use of my resources. // example function void thread_func( ... ) { scoped_lock < boost::interprocess::interprocess_mutex > my_lock( my_mutex, try_to_lock ); if( my_lock ){ cB. wait( my_lock ); // do some work cC.notify_all( ); } } Thanks in advance. I truly appreciate the help. Kish

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[random] Poisson generator
by Rupert Mazzucco 15 Sep '09

15 Sep '09

Hello, is there a reason the Poisson generator is no longer mentioned in the documentation for 1.40.0? It seems to be there and working. Cheers -- Rupert Mazzucco <mazzucco(a)iiasa.ac.at> Research Scholar, Evolution and Ecology Program IIASA - Institute for Applied Systems Analysis Schlossplatz 1, 2361 Laxenburg, Austria Phone: +43 2236 807 522 Fax: +43 2236 713 13

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[spirit] [test] Double deletion with auto-registered test suite?
by Alastair Rankine 15 Sep '09

15 Sep '09

My very simple test app (complete code below) is getting a possible double-deletion error, and it seems to have something to do with Boost Test auto-registration. Here's the error: % ./spirit2 Running 2 test cases... *** No errors detected spirit2(55443) malloc: *** error for object 0x3000101700a10: pointer being freed was not allocated *** set a breakpoint in malloc_error_break to debug zsh: abort ./spirit2 Here's the stack trace: (gdb) bt #0 0x00007fff88021b91 in malloc_error_break () #1 0x00007fff87f4b083 in free () #2 0x000000010006c3ac in boost::unit_test::framework_impl::clear (this=0x1000deec0) at framework.ipp:133 #3 0x000000010006c4aa in boost::unit_test::framework_impl::~framework_impl (this=0x1000deec0) at framework.ipp:122 #4 0x000000010006da1e in __tcf_1 () at framework.ipp:225 #5 0x00007fff87f57274 in __cxa_finalize () #6 0x00007fff87f5718c in exit () #7 0x000000010000b7bb in start () at unit_test_parameters.ipp:172 The code is compiled on MacOS X 10.6.1 with the supplied gcc 4.2 compiler. Using Boost 1.40.0 as installed by MacPorts. The Spirit guys reckon there's no heap allocation at all within their library, so that kindof points the finger at Boost Test. Also the problem goes away if you comment out one of the test cases, or remove the BOOST_AUTO_TEST_SUITE calls. Unless I'm doing something obviously wrong...? Help appreciated. #define BOOST_TEST_MODULE spirit test #include <boost/test/included/unit_test.hpp> #include <boost/spirit/include/qi.hpp> namespace qi = boost::spirit::qi; template <typename Iterator> struct MyGrammar : public qi::grammar<Iterator> { MyGrammar() : MyGrammar::base_type(sp) { using boost::spirit::char_; sp = char_(' '); } qi::rule<Iterator> sp; }; BOOST_AUTO_TEST_SUITE(SpiritTest) BOOST_AUTO_TEST_CASE(Test1) { MyGrammar<std::string::const_iterator> parser; } BOOST_AUTO_TEST_CASE(Test2) { MyGrammar<std::string::const_iterator> parser; } BOOST_AUTO_TEST_SUITE_END()

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Re: [Boost-users] Boost-users Digest, Vol 2115, Issue 4
by Dan Smithers 15 Sep '09

15 Sep '09

> Date: Fri, 11 Sep 2009 20:06:17 +0400 > From: Vladimir Prus <vladimir(a)codesourcery.com> > To: boost-users(a)lists.boost.org > Subject: Re: [Boost-users] building boost 1_33_1 > Message-ID: <h8dshm$bce$2(a)ger.gmane.org> > Content-Type: text/plain; charset=us-ascii > > Dan Smithers wrote: > >> I need to recompile boost 1_33_1 with the intel compiler icc 9.0 >> >> The jamfiles are trying to use 8 in /opt (which doesn't actually exist). >> >> Please can someone point me in the right direction to do this. Thanks for the reply. I have done some more things, and decided to try the same with boost 1.37 - the next version that I have been using. >> >> I am using >> >> ./configure CXX=icc --prefix=/vol/build --with-toolset=intel-linux >> --with-bjam=/vol/build/boost-jam-3.1.17/bin.linuxx86/bjam > > 1.33.1 is very old; and worse, it was using older version of Boost.Build. > Therefore, I'd recommend just hacking your way around in tools/build/v2/ > intel-tools.jam, or however the file is called. My problem now seems to be in the actual compilation: It tries to build in workarounds for gcc 2.95 and complains with about wrongly named header files. Possibly the problem is because I don't understand enough Jam to work out what commands are actually being run. thanks dan

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