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Regular expression problem using literals
by Neil Sutton 11 Dec '12

11 Dec '12

Hello, I am learning the basics of regular expression syntax and have been looking at the following example: #include <iostream> #include <fstream> #include <string> #include <boost/regex.hpp> #include <boost/xpressive/xpressive.hpp> using namespace boost::xpressive; int main() { std::ifstream input("myfile"); if(input) std::cout << "Success\n"; else std::cout << "fail\n"; std::string line; std::string data; while (getline(input, line)) { data += line; } std::string const &ref = data; mark_tag day(1), month(2), year(3), delim(4); sregex date = (month= repeat<1,2>(_d)) // find the month ... >> (delim= (set= '/','-')) // followed by a delimiter ... >> (day= repeat<1,2>(_d)) >> delim // and a day followed by the same >> (year= repeat<1,2>(_d >> _d)); // and the year. smatch what; if( regex_search(ref, what, date ) ) { std::cout << what[0] << '\n'; // whole match std::cout << what[day] << '\n'; // the day std::cout << what[month] << '\n'; // the month std::cout << what[year] << '\n'; // the year std::cout << what[delim] << '\n'; // the delimiter } return 0; } My problem is very simple and I am sorry to be asking about it. I want to include some literal wording in my regular expression. For example, before the program outputs the date it also searches for the words "Football results for" - (then date is output). Please can you show me how to prefix this regular expression with the literal words? My compiler see the 'for' as a c++ keyword, without more. Kind Regards

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Property Tree with boost:any
by Olivier Tristan 11 Dec '12

11 Dec '12

Hello, I'm trying to use a property tree with a boost::any like in custom_data_type.cpp from the examples folder. So far, so good. My only issue arise when I'm trying to use write_json from json_parser. I understand that boost::any do not provide direct conversion to something that can be written into a stream, but I was wondering if there is a way to provide some conversion function just like it's done for get and put inside the property tree itself. Thanks ! -- UVI <http://www.uvi.net/> Olivier Tristan| Research & Development o.tristan(a)uvi.net Facebook <http://www.facebook.com/UVI.Official> Twitter <http://twitter.com/UVIofficial> Youtube <http://www.youtube.com/user/UVIofficial> SoundCloud <http://soundcloud.com/uvi-official> Blog UVI <http://blog.uvi.net/>

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Building Boost for backwards compatibility
by Tim Burgess 11 Dec '12

11 Dec '12

Hi, I'm using Boost to build projects for the Mac. What I don't understand is how to build the libraries to support previous Mac OSX SDK versions. I'm having to build using XCode 4.5 on Mountain Lion (10.8), but want to ensure that my projects will run on 10.7 as a minimum. All advice gratefully accepted. Best wishes. Tim Burgess Raised Bar Ltd. Tel: +44 (0)1827 719822 Web: http://www.raisedbar.net

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Registration for C++Now 2013 is now open
by Boris Kolpackov 11 Dec '12

11 Dec '12

The seventh annual C++Now Conference (formerly BoostCon) will be held at the Aspen Center for Physics in Aspen, Colorado, May 12th to 17th, 2013. "We are thrilled to announce the second annual C++Now conference, the whole-language edition of BoostCon covering all the coolest topics in C++," said Dave Abrahams, Conference Co-Chair. "In 2012, we broadened the conference scope by adding a third track and offering more C++11 coverage than any other event, and the community responded with an unprecedented number of registrations. In 2013, we are going to build on that success with foundational sessions integrating what we've all learned about using C++11 during the past year, while continuing the exploration of cutting-edge topics that BoostCon attendees have come to expect." Early Bird Savings Deadlines! Early Bird conference registration, which ends April 14th, 2013, costs $599. After that date, the registration fee is $699. Register now at our registration page <http://www.eventbrite.com/event/2717332615>. Early Bird hotel registration ends December 31st, 2012 and saves $20 per night. Please reserve your room using the Aspen Meadows online reservation system <https://resweb.passkey.com/go/cplusplusnow2013> Speakers If you are interested in presenting, we are currently accepting proposals <http://cppnow.org/2013-call-for-submissions/>. Registration fee is waived for one speaker of every standard session presentation. Shorter sessions are prorated. Student/Volunteers Registration fees will be waived for a limited number of individuals that wish to attend as volunteers. Volunteer work consists of helping to run the conference and will not prevent volunteers from attending sessions. This is the first year this opportunity is being offered. If you are interested in applying to attend as a volunteer, contact us at <organizers(a)cppnow.org>. Sponsors For a copy of the conference Sponsorship Prospectus contact sponsorship(a)cppnow.org. C++Now is presented by Boost in-cooperation with ACM. Permanent link for this announcement is: http://cppnow.org/2013-registration-announcement/

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boost mpi message truncated error
by Kyle Joseph Berger 10 Dec '12

10 Dec '12

Hello, I am using boost mpi and I am having issues getting the message truncation error upon receiving a message. It is not always the same message, but it does always happen and I have been unable to figure out why. Here is the code of interest: //send particles for(int i=0;i<world.size();i++) { world.isend(i,i,particles_to_be_sent[i]); } //receive particles int receive_counter=0; boost::optional<boost::mpi::status> msginfo=world.iprobe(mpi::any_source, world.rank()); while (receive_counter<world.size()) { if (msginfo) { world.recv(msginfo->source(),world.rank(),particles_received); for (unsigned int i=0;i<particles_received.size();i++) { //add particle to its associated box in the particle grid particle_grid[particles_received[i].location_number()].insert(pair<int,Particle>(particles_received[i].global_part_num(),particles_received[i])); //check to see if the particle is contained within the box if (particles_received[i].position().y()>grid_locations[particles_received[i].location_number()].bottom() && particles_received[i].position().y()<grid_locations[particles_received[i].location_number()].top() && particles_received[i].position().x()>grid_locations[particles_received[i].location_number()].west() && particles_received[i].position().x()<grid_locations[particles_received[i].location_number()].east() && particles_received[i].position().z()>grid_locations[particles_received[i].location_number()].south() && particles_received[i].position().z()<grid_locations[particles_received[i].location_number()].north()) { //if particle is in box, then denote it as such in the particle properties particle_properties[particles_received[i].global_part_num()].particle_in_box()[particles_received[i].location_number()]=true; } } receive_counter++; } msginfo=world.iprobe(mpi::any_source, world.rank()); } I have left out variable definitions, but everything has the right type (including sending and receiving the same type-particles_to_be_sent[i] and particles_received are both vector<Particle>, where Particle is a type I've created). I thought that boost mpi is supposed to take care of making the receive buffer the right size on its own, but something isn't working here. Any help would be appreciated. Thanks, Kyle

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[exception, system] using boost::system::error_code with boost::exception
by Marco Craveiro 10 Dec '12

10 Dec '12

Hi boost users, I'm a very happy user of both error_code and exception, but now I found a new use case which is to combine them. So I'm looking for an example of how to add an error_code into an exception and get it all nicely formatted with diagnostic_information. I can see how to use error_info [1] but not error_code. Any pointers would be appreciated. Cheers Marco -- So young, and already so unknown -- Pauli blog: http://mcraveiro.blogspot.com [1] http://www.boost.org/doc/libs/1_52_0/libs/exception/doc/tutorial_transporti…

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Oven, regular and Boost
by Robert Jones 10 Dec '12

10 Dec '12

The 'Oven' port... http://dl.dropbox.com/u/1682460/git/OvenToBoost/libs/range/doc/html/range_e… makes much of its 'regular' operator, which is used to fix this problem using boost::lambda::_1; for_each_(r | filtered(_1 % 2 == 0), f); // Error! Can't default construct/copy assign for_each_(r | filtered(regular(_1 % 2 == 0)), f); // OK However, AFAICS this is not a problem in current-ishBoost (1.47). Has this ever been a problem? Can anyone comment on its general provenance? Thx, Rob.

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[Range] Sliced... less than it could be.
by Robert Jones 10 Dec '12

10 Dec '12

I was disappointed to discover that I can't write range | filtered( some_predicate ) | sliced( n, m ) | ..... because sliced requires a random access range, and filtered produces a forward range! Piffle. It seems such a useful and obvious use-case. Is this restriction really necessary? Thx, Rob.

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[overloaded_function] Why does it define f_ as const?
by Felipe Magno de Almeida 10 Dec '12

10 Dec '12

Hello, I'm trying to use overloaded_function. But unfortunately it defines f_ as const, which makes it not Assignable. Which seems to me, like a unnecessary limitation. I looked at the docs, but couldn't find any mention of assignment nor a rationale for this behavior. Is there a specific reason for overloaded_function to not be Assignable? Regards, -- Felipe Magno de Almeida

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How to implement a custom hash function for __uint128_t?
by Scott Smedley 10 Dec '12

10 Dec '12

Hi all, How can I implement a hash function for a __uint128_t type that is compatible with Boost? I tried this: #include <boost/functional/hash.hpp> #include <unordered_set> #ifdef USE_64 typedef uint64_t MyId; // works fine #else typedef __uint128_t MyId; #endif inline std::size_t hash_value (const MyId &x) { // not a very good hash function, but I just want to get it working first! return static_cast<std::size_t>(x); } int main (int argc, char *argv[]) { std::unordered_set<MyId, boost::hash<MyId>> s; s.insert(42); } but I get 144 lines of errors (!) using g++-4.7.2 with Boost v1.51.0 on 64-bit Scientific Linux 6.2: error: no matching function for call to 'hash_value(const __int128 unsigned&)' Any pointers/help would be muchly appreciated. Scott. :)

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