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graph planar_face_traversal
by Andreas Fabri 14 Feb '12

14 Feb '12

Hello, I am wondering about the output of the example on the page http://www.boost.org/doc/libs/1_48_0/libs/graph/doc/planar_face_traversal.h… I would expect that the vertices on the border of the outer or unbounded face got reported in reverse order. The vertices of inner faces are reported in clockwise order which makes that for each edge shared by inner faces, we traverse it once from source to target, and once from target to source. This does not hold for edges on the outer face. Is this intentional, or just a documentation bug? Best regards, Andreas -- Andreas Fabri, PhD Chief Officer, GeometryFactory Editor, The CGAL Project phone: +33.492.954.912 skype: andreas.fabri

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Boost Date/Time
by asif saeed 13 Feb '12

13 Feb '12

Hi, I get a run-time error when I run the following code; std::string LocaleFormattedDateTime (::boost::posix_time::ptime pt) { std::string s; std::ostringstream ss; //::boost::posix_time::time_facet * tf = new ::boost::posix_time::time_facet; ::boost::posix_time::time_facet tf; //std::locale custom_locale (std::locale(""), tf); std::locale custom_locale (std::locale(""), &tf); // custom_locale takes ownership of the tf facet ss.imbue (custom_locale); //(*tf).format("%Y%m%d-%H%M%S-%f"); // date time tf.format("%Y%m%d-%H%M%S-%f"); // date time ss << pt; // don't explicitly delete tf - what's wrong with a stack variable? why this runtime error? What is the point of new() above and //what if I don't delete allocated memory here. return ss.str(); } void CurrentDateTimeWithMicroseconds(char s[], int sz = 100) { using namespace boost::posix_time; using namespace std; using boost::date_time::date_facet; ptime t = microsec_clock::local_time(); ostringstream ss; //time_facet *df = new time_facet(); time_facet df; //std::locale loc (std::locale(""), df); std::locale loc (std::locale(""), &df); ss << LocaleFormattedDateTime(t) ; memset(s,0,sz); strcpy(s,ss.str().c_str()); } Can you tell me the problem? I modified this code after copying this from some online source. Thanks in advance, Asif

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[date_time] greg_day_of_week as numeric type
by Claude 13 Feb '12

13 Feb '12

It is possible transform or use the greg_day_of_week (day_of_week() method) as a numeric type? Also seems to me that there is no day_of_month() method. Why? -- View this message in context: http://boost.2283326.n4.nabble.com/date-time-greg-day-of-week-as-numeric-ty… Sent from the Boost - Users mailing list archive at Nabble.com.

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Re: [Boost-users] Poor/erratic boost::interprocess named_semaphore performance
by Davidson, Josh 13 Feb '12

13 Feb '12

Ok, so I converted my example to native Windows semaphores, and it consistently completes in less than 250ms (up to 160x faster). Something is definitely going on. -----Original Message----- From: Davidson, Josh Sent: Sunday, February 12, 2012 9:01 PM To: boost-users(a)lists.boost.org Subject: Poor/erratic boost::interprocess named_semaphore performance I'm experiencing performance issues using named semaphores on Windows 7 x64. Currently, I'm on 1.49 beta 1, but the behavior was similar on 1.48 and 1.47. Below, I'm copying two sample programs. They simply synchronize with one another using a pair of semaphores. To run them, start the first program and then the second. They will synchronize with each other 100k times and then the second program will spit out the elapsed time. You can restart the second program to run again without bringing down the first program. On Windows, the elapsed time the first time around is anywhere from 20 - 40 seconds. If you leave the second program running, the following run will be only about 2-3 seconds. A third run it will be back up to 20-40 seconds, and it will keep bouncing back and forth like that. On Linux, the total elapsed time is consistently less than half a second. I'm guessing the Windows implementation isn't as efficient, but I wouldn't expect it to be 100 times slower than Linux. The other perplexing thing is how wildly different the results are on Windows from run to run. =====================Test1.cpp========================================== #include <boost/date_time/posix_time/posix_time.hpp> using namespace boost::posix_time; #include <boost/interprocess/sync/named_semaphore.hpp> using namespace boost::interprocess; #include <iostream> using namespace std; int main() { named_semaphore::remove("sem1"); named_semaphore::remove("sem2"); named_semaphore sem1(create_only_t(), "sem1", 0); named_semaphore sem2(create_only_t(), "sem2", 0); while(true) { sem1.wait(); sem2.post(); } return 0; } =====================Test2.cpp========================================== #include <boost/interprocess/sync/named_semaphore.hpp> using namespace boost::interprocess; #include <boost/date_time/posix_time/posix_time.hpp> using namespace boost::posix_time; #include <iostream> using namespace std; int main() { const size_t iterations = 100000; named_semaphore sem1(open_only_t(), "sem1"); named_semaphore sem2(open_only_t(), "sem2"); ptime start = boost::posix_time::microsec_clock::local_time(); for(size_t i = 0; i < iterations; ++i) { sem1.post(); sem2.wait(); } ptime end = boost::posix_time::microsec_clock::local_time(); time_duration delta = end - start; double seconds = double(delta.total_nanoseconds())/1000000000.0; cout << "Total elapsed time: " << seconds << endl;; cout << "Time per iteration: " << (seconds/double(iterations)) << endl; return 0; }

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iterating though an inifile section using boost.property_tree
by Sean Farrow 13 Feb '12

13 Feb '12

Hi Fokes: Ok, I've got a standard windows-stle ini file. I can check that a section exists, and then get that section, using it->second, where it is declared as: boost::property_tree::ptree::const_assoc_iterator it; I've then assigned the it->second variable to a new property_tree. What I now need to do is iterate though the tree I've just assigned and get all the section keys/values. I'm using the following code to add them all to a map: std::map<string, string> SectionProps; BOOST_FOREACH(boost::property_tree::ptree::value_type &v, SectionTree) { Key =v.first; Value =v.second; SectionProps.insert(std::make_pair(Key, Value)); } It seems that even though thwe values in the ini file will be strings, of the vorm Key1=valu1 as normal, I am still getting another ptree as my second argument of the pair. How do I obtain the value from this? There are never any sub sections. Any help appreciated. Cheers Sean.

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[tuple] Tuple arithmetic
by Bill Buklis 13 Feb '12

13 Feb '12

Is there any facility to perform arithmetic operations on a tuple? For example: struct data { double a, b; }; data d1 = {1.0, 2.0}; data d2 = {2.5, 5.5}; // These two lines are not valid, but simulate what I want. boost::tie(d1.a, d1.b) *= 10.0; // Multiply each element by 10.0 boost::tie(d1.a, d1.b) += boost::tie(d2.a, d2.b); // Add the elements from the second object After calculations, d1 should equal {12.5, 25.5}; Thanks, -- Bill

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[Format] No implicit conversion to string?
by John M. Dlugosz 13 Feb '12

13 Feb '12

It's shown prominently in the docs that a boost::format object can be sent to an ostream. cout << format("%2% %1%") % 36 % 77; But, there is no easy way to use it where a plain string is needed. E.g. throw runtime_error ( format("%2% %1%") % 36 % 77 ); One must use extra parens and a named function, either throw runtime_error ( (format("%2% %1%") % 36 % 77).str() ); or throw runtime_error ( str(format("%2% %1%") % 36 % 77) ); either of which detracts from the expression. Is there any good reason why an implicit conversion operator to the matching string class was omitted? I'd like to find out if there is some reason, before looking into submitting an update. —John

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Poor/erratic boost::interprocess named_semaphore performance
by Davidson, Josh 13 Feb '12

13 Feb '12

I'm experiencing performance issues using named semaphores on Windows 7 x64. Currently, I'm on 1.49 beta 1, but the behavior was similar on 1.48 and 1.47. Below, I'm copying two sample programs. They simply synchronize with one another using a pair of semaphores. To run them, start the first program and then the second. They will synchronize with each other 100k times and then the second program will spit out the elapsed time. You can restart the second program to run again without bringing down the first program. On Windows, the elapsed time the first time around is anywhere from 20 - 40 seconds. If you leave the second program running, the following run will be only about 2-3 seconds. A third run it will be back up to 20-40 seconds, and it will keep bouncing back and forth like that. On Linux, the total elapsed time is consistently less than half a second. I'm guessing the Windows implementation isn't as efficient, but I wouldn't expect it to be 100 times slower than Linux. The other perplexing thing is how wildly different the results are on Windows from run to run. =====================Test1.cpp========================================== #include <boost/date_time/posix_time/posix_time.hpp> using namespace boost::posix_time; #include <boost/interprocess/sync/named_semaphore.hpp> using namespace boost::interprocess; #include <iostream> using namespace std; int main() { named_semaphore::remove("sem1"); named_semaphore::remove("sem2"); named_semaphore sem1(create_only_t(), "sem1", 0); named_semaphore sem2(create_only_t(), "sem2", 0); while(true) { sem1.wait(); sem2.post(); } return 0; } =====================Test2.cpp========================================== #include <boost/interprocess/sync/named_semaphore.hpp> using namespace boost::interprocess; #include <boost/date_time/posix_time/posix_time.hpp> using namespace boost::posix_time; #include <iostream> using namespace std; int main() { const size_t iterations = 100000; named_semaphore sem1(open_only_t(), "sem1"); named_semaphore sem2(open_only_t(), "sem2"); ptime start = boost::posix_time::microsec_clock::local_time(); for(size_t i = 0; i < iterations; ++i) { sem1.post(); sem2.wait(); } ptime end = boost::posix_time::microsec_clock::local_time(); time_duration delta = end - start; double seconds = double(delta.total_nanoseconds())/1000000000.0; cout << "Total elapsed time: " << seconds << endl;; cout << "Time per iteration: " << (seconds/double(iterations)) << endl; return 0; }

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How to build Boost without any libraries
by Spain, Dr. Jeffry A. 12 Feb '12

12 Feb '12

I would like to be able to build Boost 1.48.0 and install the header-only libraries without any of the libraries that require separate build and installation steps. './bootstrap.sh --without-libraries=all' doesn't work. I don't see this discussed in the getting started guide, or perhaps I am just not picking up on something obvious. Thanks for your suggestions. Jeffry A. Spain Network Administrator Cincinnati Country Day School

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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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