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boost::thread destructor and detach()
by Eric J. Holtman 01 Apr '10

01 Apr '10

It looks like the new C++ standard threading library is going to call terminate() on a thread if it's being destructed, and has not been detached or joined. Is boost::thread going to change to emulate that behavior? (Currently, it calls detach(), not terminate()). I hadn't been calling detach () in my programs when I was spinning off a thread that I didn't care about joining later. Should I be doing that, just so my code works with either library?

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[boost::numeric::functional::plus_base] Why the arguments are not const reference
by Kan Li 01 Apr '10

01 Apr '10

It seems like the operators define in boost::numeric::functional takes reference as argument instead of const reference. Which makes it compile error if I use boost::numeric::functional::plus<int, int> op; int n = op(1,1); The way to work around is boost::numeric::functional::plus<const int, const int> op; int n = op(1,1); This is very ugly and not makes much sense, compared to std::plus. So is it a design flaw or is there some other reason for designing it in this way?

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boost path???
by mh00219＠surrey.ac.uk 31 Mar '10

31 Mar '10

Hello everybody, Can you please tell me should I give the path of boost libraries in my windows PATH variable after installation.? thank you

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[serialization][Fwd: Re: Saving and reloading a container to/from disk]
by Jeff Flinn 31 Mar '10

31 Mar '10

I've forwarded this from comp.lang.c++. The OP has tried the demo.cpp example (I think), and is getting results different from those the demo says are expected. This is related to versioning... but I'm confused as to what should be the result. Jeff -------- Original Message -------- Subject: Re: Saving and reloading a container to/from disk Date: Wed, 31 Mar 2010 13:59:16 +0200 From: jacob navia <jacob(a)jacob.remcomp.fr> Reply-To: jacob(a)jspamsink.org Organization: lccwin Newsgroups: comp.lang.c++ References: <4bb2e6b3$0$15818$ba4acef3(a)reader.news.orange.fr> <81gc4oFua5U6(a)mid.individual.net> Ian Collins a écrit : > On 03/31/10 07:07 PM, jacob navia wrote: >> Hi >> >> What would be the best way to save and reload later a container >> to/from disk in C++? > > It depends, there isn't really a best way. Do you want portability? > > http://www.boost.org/doc/libs/1_42_0/libs/serialization/doc/index.html > > Is a good place to start. > Thanks. I downloaded the boost libraries, and compiled them in my machine. Unziped the source code is 269MB. Compilation took 14 minutes. Machine Mac-pro OS X with 8 CPUs and 12GB RAM. Then, I compiled the example of the serialization. The class being saved/restored looks like this: original schedule 6:24 bob 0x0x100200440 34?135'52.56" 134?22'78.3" 24th Street and 10th Avenue 0x0x1002004d0 35?137'23.456" 133?35'54.12" State street and Cathedral Vista Lane 0x0x100200530 35?136'15.456" 133?32'15.3" White House when restored, the restored stuff looks like this: 6:24 0x0x100200e30 34?135'52.56" 134?22'78.3" 24th Street and 10th Avenue 0x0x100200f40 35?137'23.456" 133?35'54.12" State street and Cathedral Vista Lane 0x0x1002012c0 35?136'15.456" 133?32'15.3" White House As you can see the name "bob" is missing. The same bug appears with all other saved/restored class instances. I am not fluent in C++ to figure out this, sorry. But maybe this is a bug in the example, I can't determine what is the reason. jacob

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boost::timer elapsed time
by Federico Golfrè Andreasi 31 Mar '10

31 Mar '10

Hi, I've read the post from Roman, and I'm not sure that I've understand. Under linux the timer.elapsed() function will not return the total time needed to do all the operations but only the CPU time, this excludes network communication in parallel programs, time spent for I/O operations ? For example if I need to measure the time needed to read an input file I should not use the timer library? What else? Thank you, Federico

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[Boost.UTF] Strange (failed) result on comparing floats
by Olaf Peter 31 Mar '10

31 Mar '10

Hi, I'm checking some data of consistence using boost's unit test framework (1.42): BOOST_CHECK_CLOSE( *v[1].y.max, -43.0e-3, std::numeric_limits<double>::epsilon() ); which fails with: difference{1.6137e-14%} between *v[1].y.max{-0.043000000000000003} and -43.0e-3{-0.042999999999999997} exceeds 2.2204460492503131e-16% where v is a std::vector,y a struct and max a boost::optional<double>. The data where parsed by boost.spirit. This is the only failed test case from 16 parsed doubles. What's gone wrong here? Do I miss something? Thanks, Olaf

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Android ndk-r3 and Boost
by Carlos 31 Mar '10

31 Mar '10

Hi!! I have been successful in compiling my app with android ndk-r2 and boost libraries. However, I have some problems in compiling my app with it with the new version of android ndk. I have done the same steps but with no results until now. I do the following steps: *1º* Building my toolchain using your instruction; *2º* Compile boost using the prebuild binary for step 1: sudo bjam install --prefix=/usr/local/boost_1_42_0 toolset=gcc-arm *3º* try to compile my program. bjam toolset=gcc-arm link=static runtime-link=static include="/home/carlos/Projectos/android-ndk-r3/build/platforms/android-3/arch-arm/usr/include" include="/usr/local/boost_1_42_0/include" library="/usr/local/boost_1_42_0/lib/libboost_system.a" library="/usr/local/boost_1_42_0/lib/libboost_thread.a" library="/usr/local/boost_1_42_0/lib/libboost_program_options.a" library="/home/carlos/Projectos/android-ndk-r3/build/platforms/android-3/arch-arm/usr/lib/libc.a" The following lines is an example of error I have: */usr/local/boost_1_42_0/include/boost/config/requires_threads.hpp:29:4: error: #error "Threading support unavaliable: it has been explicitly disabled with BOOST_DISABLE_THREADS" /usr/local/boost_1_42_0/include/boost/thread/detail/platform.hpp:67:9: error: #error "Sorry, no boost threads are available for this platform." /usr/local/boost_1_42_0/include/boost/thread/mutex.hpp:18:2: error: #error "Boost threads unavailable on this platform" /usr/local/boost_1_42_0/include/boost/asio/detail/socket_types.hpp:165: error: 'INET_ADDRSTRLEN' was not declared in this scope* I really appreciate if you could give me some help or any advice that could lead me in the right way.

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[unordered] Are unordered containers thread safe?
by Ralf Goertz 31 Mar '10

31 Mar '10

Hi, are unordered containers thread safe, e.g. can I do something like typedef boost::unordered_multimap<int, int> Map; Map m; std::vector<int> v; bool needs_to_be_erased(int val); //heavy function telling me whether val is //needed in the map; //fill m //fill v uniquely with all keys in m; int i; #pragma omp parallel for // parallelize the loop for (i=0;i<v.size();++i) { std::pair<Map::iterator,Map::iterator> r=m.equal_range(v[i]); for (Map::iterator mi=r.first;mi!=r.second;) { Map::iterator to_be_erased=m.end(); if (needs_to_be_erased(mi->second)) { to_be_erased=mi; } ++mi; if (to_be_erased!=m.end()) { m.erase(to_be_erased); to_be_erased=m.end(); } } } The reason I ask is that every once in a while the program crashes because of an assertion failure: BOOST_ASSERT(b2 == buckets_end() || !b2->empty()); (line 1018) in boost/unordered/detail/hash_table_impl.hpp function void recompute_begin_bucket(bucket_ptr b1, bucket_ptr b2). It seems as if erasing from m can cause problems even though it is guaranteed that one and the same element is never tried to be erased by different threads (they never "see" the same elements). Interestingly, the assertion failure occurs in a function for which the comment says: "This is called when a range has been erased" but I never erase ranges. Furthermore, using "schedule(dynamic)" in the omp pragma above almost always leads to one or more threads not finishing.

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edges
by Figa Pelosa 31 Mar '10

31 Mar '10

hello. My graph is an: typedef adjacency_list < mapS, vecS, undirectedS, my_vertexProperty, property < edge_weight_t, float > > Graph; I have 100 edges, and I also have an array with 100 weights. How do I assign weight[i] to edge[i], and how do I create a weightmap to use in dijkstra_shortest_paths()? Thanks a lot AC

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boost header files
by mh00219＠surrey.ac.uk 31 Mar '10

31 Mar '10

Hello , I am very new to boost libraries and infact to C++. I have very basic questions. I know that when we have a header file (.hpp) then there must also be a (.cpp) that is the implementation of the header file. But when i see the boost header files in \boost directory I dont find any .cpp files. Where are they? And what if I am using boost header files in my program then in the makefile I need to compile these header files with the corresponding .cpp files. So what path should I use for them? Waiting for your kind reply...Please reply. regards Hammad

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