September 2008 - Boost-users

static linkage of filesystem lib under linux
by Ottmar Buennemeyer 10 Sep '08

10 Sep '08

Hello, We have problems with using the static filesystem lib under linux. We use filesystem as static library in a shard library. Example: libfilesystem.a used for shared library libTestBoostStatic.so No errors during build of library libTestBoostStatic.so. Afterwards we use libtest.so in the application UseTestBoostStatic. During the linking of the application we get the following error message: Invoking: GCC C++ Linker g++ -L/home/ROSENINSPECTION/AlKeller/src/SDES/Test/TestBoostStatic/Debug -L/usr/lib64 -Wl,-static -lboost_filesystem-mt -lboost_regex-mt -Wl,-call_shared -o"UseTestBoostStatic" ./UseTestBoostStatic.o -lTestBoostStatic /home/ROSENINSPECTION/AlKeller/src/SDES/Test/TestBoostStatic/Debug/libTestBoostStatic.so: undefined reference to `boost::filesystem::detail::dir_itr_increment(void*&, void*&, std::basic_string<char, std::char_traits<char>, std::allocator<char> >&, boost::filesystem::file_status&, boost::filesystem::file_status&)' /home/ROSENINSPECTION/AlKeller/src/SDES/Test/TestBoostStatic/Debug/libTestBoostStatic.so: undefined reference to `boost::filesystem::detail::dir_itr_close(void*&, void*&)' /home/ROSENINSPECTION/AlKeller/src/SDES/Test/TestBoostStatic/Debug/libTestBoostStatic.so: undefined reference to `boost::filesystem::detail::dir_itr_first(void*&, void*&, std::basic_string<char, std::char_traits<char>, std::allocator<char> > const&, std::basic_string<char, std::char_traits<char>, std::allocator<char> >&, boost::filesystem::file_status&, boost::filesystem::file_status&)' /home/ROSENINSPECTION/AlKeller/src/SDES/Test/TestBoostStatic/Debug/libTestBoostStatic.so: undefined reference to `boost::filesystem::detail::not_found_error' collect2: ld returned 1 exit status make: *** [UseTestBoostStatic] Error 1 We use the boost version 1.34.1 GCC Version: 4.1.2 20061115 (pre release) What's wrong with our configuration? Thanks in advance, Ottmar

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[Boost_users][date_time] Updating ptime after it's been constructed
by Ryan McConnehey 10 Sep '08

10 Sep '08

Hi, Currently I'm creating a boost date_time object as follows: boost::shared_ptr<boost::posix_time::ptime> time(new boost::posix_time::ptime(boost::posix_time::microsec_clock::local_time())); Now that the ptime object has been created how do I update the boost pointer with a new local_time? There doesn't seem to be any function calls or operators that allow the setting of time. The only operators seem to allow you to offset the time not replace it. Ryan

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Re: [Boost-users] Comparing two vectors element by element
by Gevorg Voskanyan 10 Sep '08

10 Sep '08

Sean Farrow wrote: > It's not allower, the sizes aren't identical. > Sean. Then I think you can perfectly use the function below: bool bitset_vector_less( const std::vector< std::bitset< 6 > > & lhs, const std::vector< std::bitset< 6 > > & rhs ) { assert( lhs.size() == rhs.size() ); return std::equal( lhs.begin(), lhs.end(), rhs.begin(), BitSetComp() ); } where BitSetComp is the predicate you have shown earlier. HTH, Gevorg

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Periodic Timer
by amit khandelwal 10 Sep '08

10 Sep '08

I see that we have a deadline timer in boost. I am looking for a periodic timer. I see that there is a sample code in boost website to simulate a periodic timer. Over a period of time I think it will probably cause some slippage. I am looking at microsecond granularity Can someone please advise? #include <iostream> #include <boost/asio.hpp> #include <boost/thread.hpp> #include <boost/bind.hpp> #include <boost/date_time/posix_time/posix_time.hpp> class printer { public: printer(boost::asio::io_service& io) : timer1_(io, boost::posix_time::microseconds(10)), count_(0) { timer1_.async_wait(boost::bind(&printer::print1, this)); } ~printer() { std::cout << "Final count is " << count_ << "\n"; } void print1() { if (count_ < 100) { timer1_.expires_at(timer1_.expires_at() + boost::posix_time::microseconds(10)); timer1_.async_wait(boost::bind(&printer::print1, this)); std::cout << "Timer 1: " << count_ << "\n"; ++count_; } } private: boost::asio::deadline_timer timer1_; int count_; }; int main() { boost::asio::io_service io; printer p(io); boost::thread t(boost::bind(&boost::asio::io_service::run, &io)); io.run(); t.join(); return 0; } -- ------------------------------------------------------------------- Ph : (732) 647 5679 Email: khandelwal.amit(a)gmail.com Web: http://khandelwal.amit.googlepages.com/home -------------------------------------------------------------------

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[graph] Overkill to use graph library for 'small' graphs?
by Rainer Thaden 10 Sep '08

10 Sep '08

Hi all, I have to manage connections between different items in an audio control software. Currently, I am using several maps to manage "connections". I was thinking of using a graph for this but there are several questions arising. Maybe, someone can enlighten this: I am controlling a hardware which has several inputs and outputs and between it a layer of nodes. The inputs are connected to the nodes as well as the outputs. An input can be connected to several nodes, an output only to one node. So, the graph has to represent connections between inputs, nodes, and outputs. (Actually, there are more layers, but to keep it simple I show only these 3). The inputs, outputs, etc. in the end are integers, which are sent to the device. I represent them as enums. So I have, e.g. enum Inputs{ Input1 = 0, Input2, InputNone }; enum Nodes{ NodeM=0, NodeN, NodeNone }; enum Outputs{ AnalogOut1 = 0, AnalogOut2 OutputNone }; Now, to use graphs, I have to define vertices. These have to be of "one" type, as far as I understand that. How do I use the enums as shown above? A vertice-value may be in enum Inputs or Nodes or Outputs. Do I have to use a graph with elements of type ints and cast them to my enums? From the introduction to BGL, modified: const int num_vertices = InputNone + NodeNone + OutputNone; // writing out the edges in the graph typedef std::pair<int, int> Edge; Edge edge_array[] = { Edge(Input1,NodeM), Edge(Input2,NodeN), Edge(AnalogOut1,NodeM), Edge(AnalogOut2,NodeN)}; const int num_edges = sizeof(edge_array)/sizeof(edge_array[0]); // declare a graph object Graph g(num_vertices); // add the edges to the graph object for (int i = 0; i < num_edges; ++i) add_edge(edge_array[i].first, edge_array[i].second, g); When I e.g. need all vertices, connected to NodeM, I get two ints. One of them represents a member of enum Inputs, the other one a member of enum Outputs. Their numbers overlap, so I can not tell which is an Input and which is an Output (the hardware device needs the numbers starting from 0). Any idea how do solve this? Secondly, is there a big advantage of using a graph? There are about 25 different inputs, 8 nodes and 10 outputs and 2-3 additional layers. It may be more elegant to use one graph instead of several maps. I can not estimate the effort and performance of the graph. Would it be overkill in both, performance and time to implement to use a graph for that? Thanks in advance and regards, Rainer

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Re: [Boost-users] Comparing two vectors element by element
by Gevorg Voskanyan 10 Sep '08

10 Sep '08

Sean Farrow wrote: > Hi Gevorg: > In this case it's the second, for more background for interest: > Each vector represents a braille cell. > A braille cell has 6 dots hence the std::bitset<6> so: > A vector can have up to 6 bitsets, each bitset represents one dots > state. > Hth. > Sean. Ok, what happens when a vector having 4 bitsets is compared with one having 6: - 4 bitsets of the first vector are compared with the first 4 bitsets of the second vector, ignoring last 2 elements? - The first vector is considered the lesser because it has fewer elements? - Is this not allowed? - something else? Best Regards, Gevorg

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Boost.spirit, boost.tokenizer or boost.regex
by Sean Farrow 10 Sep '08

10 Sep '08

Hi: I am currently in the process of needing to transform some input. I need to transform voice commands passed to a dll to strings of text inserted to an application. One voice command might be: "skip 5 lines". In this case the skip translates o sk, the 5 remains as it is, and there is nothing printed for the lines part of the command. Which boost library would be the best suited to this, boost.regex, boost.tokenizer or boost.spirit? Cheers Sean. __________ Information from ESET NOD32 Antivirus, version of virus signature database 3431 (20080910) __________ The message was checked by ESET NOD32 Antivirus. http://www.eset.com

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Re: [Boost-users] Comparing two vectors element by element
by Gevorg Voskanyan 10 Sep '08

10 Sep '08

Sean Farrow wrote: > Hi: > The code doesn't compile here as std:bitsetdoesn't define the < > operator according to visual studio. I have a custom operator defined as > a structure: > struct BitSetComp > { > bool operator()(const std::bitset<6>& lhs, const std::bitset<6>& > rhs) const > { > return lhs.to_ulong() < rhs.to_ulong(); > } > }; > How can I use this in the code you providee, or do I need to redefine in > a certain way? > Cheers > Sean. [snip] Hi Sean, The answer depends on how you define one vector being less than another. E.g. given the following vectors: typedef std::bitset< 6 > my_bitset; typedef std::vector< my_bitset > my_bitset_vector; my_bitset_vector v1 = { my_bitset( "1100" ), my_bitset( "1101" ) }, v2 = { my_bitset( "1110" ), my_bitset( "1000" ) }, v3 = { my_bitset( "1101" ), my_bitset( "1111" ), my_bitset( "1010" ) }, v4 = { my_bitset( "1100" ), my_bitset( "1101" ), my_bitset( "1001" }; how shall these vectors compare to each other? #1. Lexicographical comparison - v1 < v2 is true, v1 < v3 is true, v2 < v3 is false, v1 < v4 is true, ... #include <algorithm> bool bitset_vector_less_1( const my_bitset_vector& lhs, const my_bitset_vector& rhs ) { return std::lexicographical_compare( lhs.begin(), lhs.end(), rhs.begin(), rhs.end(), BitSetComp() ); } #2. Each element of the first vector shall be less than the correponding element of the second vector - v1 < v2 is false, v2 < v1 is false, v4 < v3 is true, (here it is not immediately clear how would one compare vectors of different size such as v1 and v3) bool bitset_vector_less_2( const my_bitset_vector& lhs, const my_bitset_vector& rhs ) { assert( lhs.size() == rhs.size() ); return std::equal( lhs.begin(), lhs.end(), rhs.begin(), BitSetComp() ); } If you mean something else, explain your requirement with more detail and I will try to offer some more help. HTH, Best Regards, Gevorg P.S. Sorry but the answer is not strictly boost-related

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Comparing two vectors element by element
by Sean Farrow 10 Sep '08

10 Sep '08

Hi: I need to compare two vectors. I already have a function to compare two individual elements (std::bitsets) in this case. Can I use boost.foreach to do this, or is there a better way. I need to know whether vector one, is less than vector two. Any help apreciated. Cheers Sean. __________ Information from ESET NOD32 Antivirus, version of virus signature database 3428 (20080909) __________ The message was checked by ESET NOD32 Antivirus. http://www.eset.com

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[asio] Error: terminate called after throwing an instance of
by Fabio Locati 10 Sep '08

10 Sep '08

Hi guys, I'm a new user of boost, and even newer of boost.asio. I create this code: http://codepad.org/DXLhsEtW (read.cpp) http://codepad.org/xlGDzgDC (read.h) http://codepad.org/DayP6oOB (http.h) and when I compile with: c++ read.cpp -o read /usr/local/lib/libboost_regex-gcc42-mt-1_36.so -I /usr/local/include/boost-1_36/ /usr/local/lib/libboost_system-gcc42-mt.so -O3 it compiles without any problems, but when I run it, it returns this: http://codepad.org/ad96WiPp I'm not getting why, someone have some idea? Thankyou for your time, Fabio A Locati

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