- Boost-users - lists.boost.org

Example of using posix_time with timezone
by Archie14 21 May '09

21 May '09

This post is related to my discovery of differences in behavior between posix_time::from_ftime and C# DateTime.FromFileTime methods (earlier post) Now I am trying to learn the proper usage of posix_time and time_zones. After reading the documentation I am still confused regarding usage of the timezone together with usage of classes/functions in posix_time namespace Is it possible to do smth.like this: First declare the time zone, like EST, CT ets and then all subsequent calls to posix_time namespace functions or classes will take this timezone as a base? I will really appreciate a simple example of specifying EST timezone for posix_time.

1 0

[multi_array] Looking for elegant way to convert between array and extent_gen objects
by Oei, YC 21 May '09

21 May '09

Dear list members, I've been working with multi_array lately, and am trying to exclusively use boost::arrays as the indexing object when accessing multi_arrays, in order to keep my code dimension-independent. There is a little issue however, in that not all multi_array methods take arrays as parameters; e.g. multi_array::resize() only takes an extent_gen parameter. I've come up with a workaround, which converts an array to the corresponding extent_gen object, and this works.... but it is an ugly amount of code for such a little task. I was hoping I might ask if you have better suggestions? Is there a way to make extents-notation dimension-independent? The content of the header file with my current solution is pasted below to illustrate what I'm trying to achieve - a (somewhat overly trivial) use case is as follows: #include "ArrayToExtentGen.h" [...] boost::multi_array<SomeValueType, SomeNumberOfDimensions> array; [...] boost::array<boost::multi_array_types::index, SomeNumberOfDimensions> position = {{0, 0, 0, 0, 0, 0, 0, 0}}; array.resize(ArrayToExtentGen(position)); [...] Thanks for your thoughts! Yung-Chin -- ArrayToExtentGen.h -- #ifndef GUARD_ArrayToExtentGen_h #define GUARD_ArrayToExtentGen_h #include <boost/array.hpp> #include <boost/multi_array.hpp> namespace YungChin { //! Helper class for ArrayToExtentGen() to recurse through dimensions template < size_t NumDimsIn, size_t NumDimsOut> class ArrayToExtentGenRecurse; //! Convert boost::array (used for addressing on multi_array) into extent_gen template<size_t NumDims> boost::detail::multi_array::extent_gen<NumDims> ArrayToExtentGen( const boost::array<boost::multi_array_types::index, NumDims>& array) { return ArrayToExtentGenRecurse<NumDims, NumDims>::Apply(array); } //ArrayToExtentGen template < size_t NumDimsIn, size_t NumDimsOut> class ArrayToExtentGenRecurse { public: static boost::detail::multi_array::extent_gen<NumDimsOut> Apply( const boost::array<boost::multi_array_types::index, NumDimsIn>& array) { return ArrayToExtentGenRecurse<NumDimsIn, NumDimsOut-1> ::Apply(array)[array[NumDimsOut-1]]; } //Apply }; //ArrayToExtentGen //! Partial specialisation of the above, to stop recursing at 0 dimensions template <size_t NumDimsIn> class ArrayToExtentGenRecurse<NumDimsIn, 0> { public: static boost::detail::multi_array::extent_gen<0> Apply( const boost::array<boost::multi_array_types::index, NumDimsIn>& array) { return boost::detail::multi_array::extent_gen<0>(); } //Apply }; //ArrayToExtentGen } //namespace YungChin #endif

1 0

posix_time::from_ftime versus DateTime.FromFileTime
by Archie14 21 May '09

21 May '09

I will appreciate any help in sorting out following issue: There is a value dt of type long. Calling boost::posix::time::from_ftime in c++ and DateTime.FromFileTime with that value produce "slightly" different results: dt = 128822886020000000 c++: "2009-Mar-23 13:30:02" c#: {3/23/2009 9:30:02 AM} What I am doing wrong? c++ code: typedef signed __int64 int64; int64 dt = 128822886020000000; datetime = boost::posix_time::from_ftime<boost::posix_time::ptime>(dt); std::string testdt = boost::posix_time::to_simple_string(datetime); C# code: Int64 dt = 128822886020000000; startdate = DateTime.FromFileTime(dt);

2 1

Re: [Boost-users] Boost.Unordered throws 64-bit portability warnings
by JOAQUIN M. LOPEZ MUÑOZ 21 May '09

21 May '09

________________________________________ De: boost-users-bounces(a)lists.boost.org [boost-users-bounces(a)lists.boost.org] En nombre de Daniel James [daniel_james(a)fmail.co.uk] Enviado el: jueves, 21 de mayo de 2009 21:36 Para: boost-users(a)lists.boost.org Asunto: Re: [Boost-users] Boost.Unordered throws 64-bit portability warnings 2009/5/21 Dominique Devienne <ddevienne(a)gmail.com>: > > > > FWIW, I'm getting these as well when using > > boost::hash_combine(hash_value(this->member_)); to implement hashes > > for my classes. We also use VS2005 with the compiler switch that > > raises these warnings. My work around below is not pretty... --DD > > > > #if ACME_SIZEOF_SIZE_T == 4 > > // Avoid warning C4267: 'argument' : > > // conversion from 'size_t' to 'unsigned int', possible loss of data > > boost::hash_combine( > > seed, static_cast<unsigned int>(hash_value(member_)) > > ); > > #else > > boost::hash_combine(seed, hash_value(member_)); > > #endif > > Doesn't 'boost::hash_combine(seed, member_)' work? > > I'll have a look at the warning when I get the chance, but AFAICT > they're wrong since when compiling for 64-bit a different overload or > template resolution would be chosen. Is this maybe related to http://lists.boost.org/boost-users/2007/03/26388.php ? Joaquín M López Muñoz Telefónica, Investigación y Desarrollo

1 0

iterators must go
by Neal Becker 21 May '09

21 May '09

Interesting presentation: http://www.boostcon.com/site- media/var/sphene/sphwiki/attachment/2009/05/08/iterators-must-go.pdf

8 13

Persisting __int64 (or long long) with boost::serialization?
by Sandy Walsh 21 May '09

21 May '09

Hi, Sorry for the n00b question, but I'm trying to serialize some unsigned __int64 member variables using boost::serialization. I added the following to my header: namespace boost { namespace serialization { template<class Archive> void load(Archive & ar, unsigned __int64& big, const unsigned int version) { size_t size = sizeof(big); ar.load_binary(&big, size); } template<class Archive> void save(Archive & ar, unsigned __int64 big, const unsigned int version) { ar & sizeof(big); ar.save_binary(&big, sizeof(big)); } } }; But the compiler still complains that it doesn't know how to handle that right-hand operand. Is there something obvious here I'm missing? Thanks -S

4 6

Declare statistical distribution array: boost/math/distributions
by Alex Tsoi 21 May '09

21 May '09

Hi all, I am trying to write a MCMC algorithm by using boost's math distribution library, what I want to do is to first declare an array of length 10 of gamma distribution, and then run a for loop to declare each gamma distribution's parameters. However, boost does not allow me to declare the gamma distribution array without having defining the parameter in advance: gamma_distribution<double> mydist10[10]; error: no appropriate default constructor available. because the library requires to know the parameter of the gamma distribution in advance. Do you guys have any idea to overcome this ? Thanks a lot for any comment or suggestion. Alex- -- Lam C. Tsoi (Alex) Medical University of South Carolina

3 3

Boost'Con aftermath
by Joel Falcou 21 May '09

21 May '09

I wanted to know what will the paper submitted to boost'con become ? Is there any publication planned or not ? Just asking to know if I can quote the thing I did for Boost'Con 09 in other papers ;) Regards -- ___________________________________________ Joel Falcou - Assistant Professor PARALL Team - LRI - Universite Paris Sud XI Tel : (+33)1 69 15 66 35

2 2

boost::iostreams filter question
by plarroy 21 May '09

21 May '09

Hello, I have implemented a test SymmetricFilter and works ok. Although to my suprise I had to declare two different methods of filter differing only in the signature by the const char*& src_end. If I supress either of those i get a compile time error. Perhaps it is because it's being used as a bidirectional filter? as the two signatures might be the ones in boost/iostreams/filter/symmetric.hpp read and write? Pedro. Regards. My code: class smashing_filter_impl { public: typedef char char_type; smashing_filter_impl() { } bool filter(const char*& src_begin, char*& src_end, char*& dst_begin, char*& dst_end, bool flush) { bool eof = false; ptrdiff_t src_sz = src_end - src_begin; if( src_sz <= 0 ) return false; while(src_begin < src_end && dst_begin < dst_end) *dst_begin++ = tolower(*src_begin++); return true; } bool filter(const char*& src_begin, const char*& src_end, char*& dst_begin, char*& dst_end, bool flush) { bool eof = false; ptrdiff_t src_sz = src_end - src_begin; if( src_sz <= 0 ) return false; while(src_begin < src_end && dst_begin < dst_end) *dst_begin++ = tolower(*src_begin++); return true; } void close() {} private: }; struct smashing_filter : symmetric_filter<smashing_filter_impl> { public: typedef symmetric_filter<smashing_filter_impl> base_type; smashing_filter() : base_type(default_device_buffer_size) { } };

1 0

Boost Library on ThreadX RTOS
by Suraj Gupta, Gurgaon 21 May '09

21 May '09

Hi All, I want to use BOOST library (Test) on ThreadX Real Time Operating System. Can it be used on ThreadX? If possible, are there any guidelines those needs to be followed? Thanks, Suraj DISCLAIMER: ----------------------------------------------------------------------------------------------------------------------- The contents of this e-mail and any attachment(s) are confidential and intended for the named recipient(s) only. It shall not attach any liability on the originator or HCL or its affiliates. Any views or opinions presented in this email are solely those of the author and may not necessarily reflect the opinions of HCL or its affiliates. Any form of reproduction, dissemination, copying, disclosure, modification, distribution and / or publication of this message without the prior written consent of the author of this e-mail is strictly prohibited. If you have received this email in error please delete it and notify the sender immediately. Before opening any mail and attachments please check them for viruses and defect. -----------------------------------------------------------------------------------------------------------------------

1 0