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Boost timer library : formatting a cpu_times value always prints zeros ?
by Jean-Francois Romang 12 Feb '12

12 Feb '12

Hello, I'm trying to use the boost::timer library, but I can't get to 'format' function to work : it always prints zero values. I followed the documentation : http://www.boost.org/doc/libs/1_48_0/libs/timer/doc/cpu_timers.html#Default… Here is my code : { boost::timer::cpu_timer cput; someFunctionTakingTime(); std::cout<<cput.elapsed().user/1000000000.0<<std::endl; std::cout<<cput.format(3,"%ws\n")<<std::endl; } Here is the result I get : 0.390002 0.000s Using auto_cpu_timer does not help. Is there something wring in my code ?

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Tokenizer Vs. String Algos
by asif saeed 12 Feb '12

12 Feb '12

Hi, I haven't looked into the code but I wonder if just using string algos would be faster than using Tokenizer in that I can customize. Best regards, Asif

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Tokenizer / offset_separator
by asif saeed 12 Feb '12

12 Feb '12

Hi, I created a class template where the template parameter, which is the size of the array, is used to create a static array of offsets (for offset_separator) in a static function (offsets()) returning a const reference to that local static array. I then call create offset_separator like this: offset_separator sep(offsets(), offsets+T); However, if I have observed it correctly, offset_separator (1.47.0) seems to copy the sequence of offsets into an internal vector. What's wrong with just using the passed array? Best regards, Asif

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[uBLAS] Strange bug with nvcc
by Chris Jewell 12 Feb '12

12 Feb '12

Hi all, I have a weird bug with the CUDA compiler nvcc (v. 4.1, Linux) and Boost::uBLAS (1.48.0). I need to copy data out of uBLAS vectors/matrices into GPU space, hence I need to compile a file containing Boost::ublas structures as well as CUDA code -- hence compiling Boost::uBLAS with nvcc. I am including ublas/operation.hpp, ublas/matrix.hpp, ublas/matrix_sparse.hpp, ublas/matrix_proxy.hpp, ublas/vector.hpp, and ublas/io.hpp. The underlying version of GCC is 4.3.2 on a Suse Linux platform. If I comment out all the CUDA code and compile with raw g++, then everything is fine. However, if I compile with nvcc, then I get many errors like the following: /home/stats/stsiab/include/boost/numeric/ublas/vector_sparse.hpp: In member function ‘const T* boost::numeric::ublas::mapped_vector<T, A>::find_element(typename A::size_type) const’: /home/stats/stsiab/include/boost/numeric/ublas/vector_sparse.hpp:390: error: ‘__T13’ has not been declared What is "__T13"? grep on the Boost source doesn't find it, so I assume that I'm missing a header from somewhere else? The other odd thing is that there is no reference to my CUDA file. Furthermore, everything works well on my MacBook Pro with GCC 4.2.1 and nvcc 4.1. Any ideas? Thanks, Chris -- Dr Chris Jewell Department of Statistics University of Warwick Coventry CV4 7AL UK Tel: +44 (0)24 7615 0778

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std:string to boost::filesystem::path, then, create directories.
by JIA Pei 11 Feb '12

11 Feb '12

Hi, all: After upgrading to boost 1.48.0, my code seems to stopping working. The original code is pretty simple: char* folderName = "./test"; if (!boost::filesystem::is_directory( folderName ) ) boost::filesystem::create_directories( folderName ); It used to work fine but after upgrading to boost 1.48.0, I got the following annoying errors always: Unhandled exception at 0x51d8ee9e (msvcr90d.dll) in myTest.exe: 0xC0000005: Access violation writing location 0xcdcdcdcd. The program stops at the line "if (!boost::filesystem::is_directory( folderName ) )", and the call stack seems to hint it's an error coming from memcpy.asm " TrailUp1: mov al,[esi] ;U - get byte from source ;V - spare mov [edi],al ;U - put byte in destination mov eax,[dst] ;V - return pointer to destination pop esi ;U - restore esi pop edi ;V - restore edi M_EXIT " Can anybody help me out? Thank you very much.... Best Regards Pei -- Pei JIA Email: jp4work(a)gmail.com cell: +1 604-362-5816 Welcome to Vision Open http://www.visionopen.com

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[asio] compiling on cygwin
by Red Taza 11 Feb '12

11 Feb '12

Hi,I have a program that works fine on Solaris and Linux and I want to port it to work to on Cygwin, but am having issues getting Boost.asio to compile.The problem is it wants me to set some defines which I believe makes it use the native Windows socket interface (winsock) where as I want it to use the Cygwin socket interface because the program uses other libraries that expect the Cygwin socket interface. I want to be able to compile a program like this: $ cat prog.cc #include <net-snmp/net-snmp-config.h>#include <net-snmp/net-snmp-includes.h>#include <net-snmp/agent/net-snmp-agent-includes.h>#include <boost/asio.hpp> int main() {} $ To get the above code to compile when only including boost/asio.hpp I have to use the following: g++ -D_WIN32_WINNT=0x0501 -D__USE_W32_SOCKETS \ -I$BOOST_ROOT/include -I$NETSNMP_HOME/include \ prog.cc \ -L$BOOST_ROOT/lib -lboost_system -lws2_32 But the net-snmp headers fail when added, where as when I remove the include for the asio header file and remove -D_WIN32_WINNT=0x0501, -D__USE_W32_SOCKETS and -lws2_32 from the compile line then the net-snmp headers compile fine - but the asio will fail.g++ -I$BOOST_ROOT/include -I$NETSNMP_HOME/include prog.cc -L$BOOST_ROOT/lib -lboost_system Is there a define I can set so that boost.asio uses the Cygwin sockets? I would have thought that this would be the expected behaviour when compiling on Cygwin. The version of Cygwin is:$ uname -aCYGWIN_NT-6.0 toshiba-PC 1.7.10(0.259/5/3) 2012-02-05 12:36 i686 Cygwin The version of boost is:boost_1_48_0 Thanks

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How to make Boost.Format fault tolerant?
by John M. Dlugosz 11 Feb '12

11 Feb '12

A common case for using Boost.Format is in the production of error or warning messages. So, these don't get run on a normal use of the program, and problems with the arguments will go unnoticed until there _is_ an error, in which case I get (at best) no error message, or worse, turn a log-only warning statement into an exception. Does Format already have some features to make it not throw exceptions? Idealy, for messages that go into a log or are used to diagnose some program bug, any information is better than none and I'd like to see what it did get as best as it can, and not worry about how pretty it may be. So missing arguments use a default placeholder text instead, and extra arguments without specifiers in the format string just get appended with spaces in between, and any formatting spec error just goes back to default string, and any error during that gives a placeholder but the other arguments are processed. —John

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Boost.Graph DFS and TerminatorFunc
by John Eddy 10 Feb '12

10 Feb '12

Is there a good reason that the TerminatorFunc template parameter of the depth_first_visit is not exposed through the DFS function? It would be easy to do and very helpful to me. I'd rather not modify my version of the boost code especially if this would be generally useful to others. Thanks! John

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Tokenizer / offset_separator misbehaving - boost 1.47.0 / Windows 2003 Standard Server 32-bit / Visual C++ 2010 Express
by asif saeed 10 Feb '12

10 Feb '12

Hi, I wrote the following code to test offset_separator //////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////// int main (int argc, char **argv) { using namespace std; typedef boost::offset_separator sep_type_t; typedef boost::tokenizer<sep_type_t> tokenizer_t; typedef tokenizer_t::const_iterator const_iterator; typedef tokenizer_t::iterator iterator; const string sentence = "Marry had a little lamb!"; int endMarkers[] = {5,3,1,6,4}; sep_type_t sep(endMarkers,endMarkers+3); tokenizer_t t_(sentence,sep); for (tokenizer_t::iterator i=t_.begin();i!=t_.end();++i) cout << endl << *i; return 0; } //////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////// I get the following result: Marry ha d a li ttl e lamb ! Any idea how I can fix it? I want each token on a separate line. I am providing zero-based end indices to separator. Thanks in advance, -Asif

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boost-introduced ambiguity in _1/_2 etc.
by Piotr Wyderski 10 Feb '12

10 Feb '12

Hello, I am refactoring our application which uses boost extensively in order to replace some boost-provided entities with their std counterparts defined in the C++11 standard. I've experienced a problem related to boost::bind placeholders defined in placeholders.hpp. The file begins with: namespace { static inline boost::arg<1> _1() { return boost::arg<1>(); } [...] unconditionally injecting the _N() functions into the global namespace scope. When I type "using namespace std::placeholders;" in order to use e.g. std::placeholders::_1, an unsolvable ambiguity occurs, as there is no way to transfer the boost-defined variants into an uncolliding namespace. Could you please add a macro in 1.49 which would allow me to override the default behaviour and define the functions in boost:: or boost::placeholders namespaces? #if defined(BOOST_USE_BOOST_PLACEHOLDERS_NAMESPACE) namespace boost { #else namespace { [...] Best regards, Piotr

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