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type_with_alignment<5> ?
by Gottlob Frege 13 Jun '06

13 Jun '06

I'd like type_with_alignment<> to handle sizes between 'true' alignments, and/or have a way to map 'in bwetween' alignments to their lower alignment. ie I have a struct of unknown type, but known size = 5. What is it's alignment? You could 'punt' and say max_align, but I suggest that its alignment is <= 5 (ie probably 4 for a typical platform). ie imagine that the struct might have an int as it's first member, but can't have a double (assuming sizeof(double) > 5), so the alignment might need to be alignment_of<int>, but can't be alignment_of<double>. Does this assumption hold true? So how can I map (at compile time) an integer 'n' to the closest 'x' <= n where x is from the set S, and where S is the set of possible alignments? Tony

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Re: [Boost-users] [boost.multi_array] Best use of memory
by Ronald Garcia 13 Jun '06

13 Jun '06

Hello Sebastien, Ideally, you should be able to work with an array of doubles, rather than an array of pointers to double. I can create an multi_array with the dimensions you mention. To answer your questions, multi_array uses a standard library allocator to allocate a contiguous block of memory in which to hold the array data. I'm afraid I do not know why you cannot exceed these limits. ron > I'm currently using multi_array to represent 3D matrices of doubles, I > was wondering which would be the best use since the array has to > hold a > very large amount of data. I' currently testing whith a multi_array of > 800x800x100 to hold double or pointers to double and I have memory > problems. When I declare the multi_array whith pointers to doubles > I can > usually go up to 775x775x100 without problems but when I try the same > thing with a multi_array of doubles I get a bad alloc error. My real > needs for the moment are for a multi_array of 800x600x57 but I will > need > bigger storage capacity in the near future, what are your sugesstions. > Is the multi_array a pointer itself? > How is memory management handled? > How can go beyond these limits? > > > > -- > Sébastien Fortier

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[Tokenizer] Separate by multiple characters?
by Stian Karlsen 13 Jun '06

13 Jun '06

Hi. Can the Boost Tokenizer be used to split a string with a delimiter of several characters? With this I mean that the delimiter ";;" would split ("12;3;;45") into ("12;3","45"). I can't find functions etc for this in the documentation and the examples. Is there any other class that does this easily? Best Regards, Stian

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how to turn on multiline option of boost::regex_search() algorithm
by Renjie Zhao 13 Jun '06

13 Jun '06

Can any one tell me how to specify "Multiline" search while using regex? e.g. std::string fb; // fb stores a fragment of html code, multiline; boost::regex pattern("</tr>\r\n</table>\r\n</td>\r\n</tr>\r\n</table>\r\n</td>\r\n</tr>\r\n</table>"); boost::smatch res; boost::match_flag_type flags = boost::match_default; std::string::const_iterator s , e; s = fb.begin(); e = fb.end(); if(boost::regex_search(s, e, res, pattern, flags)) { //process the match. } else { //I am always here } When I use some other regex tools to check the same target string and match pattern string, I always get the right thing as expected. How can I alter the option of boost::regex_search to satisfy the original request? thanks -- This is my Very Signature. Ha, pretty good?

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Link options(TO DALE MCCOY)
by umut tabak 13 Jun '06

13 Jun '06

Dear, Sorry for replying to a specific person since the reply link is not operational for me(at least). g++ -c -I/usr/local/include/boost-1_33_1 filename.cc -c option only creates the linkable object file(correct me if I am mistaken so you have link some libraries to get the proper exe file(I am under XP now)) but -c option does not call the linker. I have chosen both boost and boost devel packages for install under Cygwin. I was using the same code under linux with the following link options g++ -g -o filename filename.cc -I/usr/local/opt/boost_1_33_1/include/boost-1_33_1/ -L/usr/local/opt/boost-1_33_1/lib -lboost_filesystem-gcc So I was linking to the boost_filesystem-gcc library. I tried the same but it gave errors, Regards,

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bjam under cygwin/XP
by Janos Vegh 13 Jun '06

13 Jun '06

Hi, I am trying to use bjam, through building a 'hello' project. However, I receive the following: $ bjam Unable to load Boost.Build: could not find build system. --------------------------------------------------------- C:\cygwin\home\Veghj\projects\hello\boost-build.jam attempted to load the build system by invoking 'boost-build /cygdrive/c/veghj/projects/boost_1_33_1/tools/build/v2 ;' but we were unable to find "bootstrap.jam" in the specified directory or in BOOST_BUILD_PATH (searching /cygdrive/c/veghj/projects/boost_1_33_1/tools/ build/v2). Please consult the documentation at 'http://www.boost.org'. At the same time, the requested file is apparently there: $ ls /cygdrive/c/veghj/projects/boost_1_33_1/tools/build/v2 boost-build.jam example release_procedure.txt boost.css generators_prototype.py roll.sh bootstrap.jam hacking.txt site-config.jam build index.html test build-system.jam kernel tools changes.txt nightly.sh user-config.jam debian notes util doc options What do I wrong? Thanks for any help Janos

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Linking with the appropriate library component
by Umut TABAK 13 Jun '06

13 Jun '06

Dear all, I have tried to install boost by the packages that are supplied as a part of Cygwin which kept me doing a lot of work. Anyway, to test the library(lexical_cast) I have a very simple code, for the moment I can compile the file and the .o file is succesfully written, but in the link process I could not figure out which library and/or options I have to use. I have the obj file but can not produce an exe file. I used g++ -c -I"C:\cygwin\usr\local\include\boost-1_33_1\boost" filename.cc and filename.o is in the directory. Can somebody share his/her ideas with me. Best regards, Umut

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Compilers supported by a given library
by Edward Diener 13 Jun '06

13 Jun '06

Is there any central place in the Boost documentation which tells, for any given release, or even just for the latest release, which compilers are supported by a given library ? I ask this because attempting to build a particular library in Boost 1.33.1 for a particular compiler failed, and I could see no place where I could determine whether that Boost library was actually meant to support the particular compiler or not in the 1.33.1 implementation.

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[BGL] Betweenness Centrality Clustering
by Rui Carvalho 12 Jun '06

12 Jun '06

Hello, I'm trying to implement the algorithm in the paper below and I'd like to know if I need to do it myself, or whether it has been implemented as part of the BGL as 'Betweenness Centrality Clustering'. Could someone help, please. I just don't want to reinvent the wheel. Cheers, Rui > -----Original Message----- > From: Rui Carvalho [mailto:rui.carvalho@ucl.ac.uk] > Sent: 07 June 2006 23:48 > To: 'boost-users(a)lists.boost.org' > Subject: [BGL] Betweenness Centrality Clustering > > Hi, > > Is the BGL betweenness centrality clustering algorithm an implementation of: > > Community structure in social and biological networks > M. Girvan and M. E. J. Newman > Proc. Natl. Acad. Sci. USA 99, 7821-7826 (2002). > http://aps.arxiv.org/PS_cache/cond-mat/pdf/0112/0112110.pdf > > thanks, > Rui

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gzseek equivalent in boost::iostreams with bzip2/gzip?
by Hin-Tak Leung 12 Jun '06

12 Jun '06

What I would like to do is to skip over part of a gzip'ed input, in a manner similiar to calling gzseek() in C, but I don't seem to be able to do that. Since it is possible to do it in C (somewhat slowly and there is no bzseek), I was thinking of something similiar to: namespace boost_io = boost::iostreams; boost_io::filtering_istream *instr = new boost_io::filtering_istream(); /* one of these two */ //instr->push(boost_io::gzip_decompressor()); instr->push(boost_io::bzip2_decompressor()); instr->push(boost_io::file_source(m_FileName.c_str(), std::ios::in | std::ios::binary)); // skip the header //instr->seekg(boost_io::offset_to_position(m_iHeaderBytes), std::ios_base::beg); instr->seekg(boost_io::offset_to_position(m_iHeaderBytes)); int32_t datasize = BUFFER_ZIZE; m_lpData = new char[datasize]; std::cout << "position before:\t " << instr->tellg() << std::endl; instr->read(m_lpData, datasize); std::cout << "position after:\t " << instr->tellg() << std::endl; But I tellg() returns 0 and datasize without the push::decompressor, and -1/-1 when the decompressor is pushed. Am I doing something wrong? I know streams aren't really seekable, but I was hoping that there is a poorman's seek (like gzseek - which is essentially read and throw-away) that's implementable. The incentive - is to have transparent decompression of input in some legacy code - I don't really want to modify every read to gzread, or bzread, for example... Thanks a lot. Hin-Tak Leung Send instant messages to your online friends http://uk.messenger.yahoo.com

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