NUL char in strings in C++
std::string is not a null terminated string. If you want to empty it use the clear() method. If you want to remove an element of the string use the erase() method.
c++11
How do I give streams better exception messages?
Boost is an open source project so the way I see it there are 2 options: Complain. Either write a bug report or get on the mailing list and suggest an enhancement or both. If the community thinks you have a good point, someone might take it on Do 1, then do something about it. … Read more
C++11 atomic memory ordering – is this a correct usage of relaxed (release-consume) ordering?
Why are you loading the old flags value twice in your CAS loops? The first time is by flags.load(), and the second by the compare_exchange_weak(), which the standard specifies on CAS failure will load the previous value into the first argument, which in this case is flagsNow. According to http://en.cppreference.com/w/cpp/atomic/atomic/compare_exchange, “Otherwise, loads the actual value … Read more
Detecting constexpr with SFINAE
NOTE: I opened a question here about whether OPs code is actually valid. My rewritten example below will work in any case. but I would like to know if the code is legal C++11 It is, although the default template argument may be considered a bit unusual. I personally like the following style better, which … Read more
What happens if ‘throw’ fails to allocate memory for exception object?
(providing my own answer… I’ll wait for few days and if there are no problems with it — I’ll mark it as accepted) I spent some time investigating this and here is what I unearthed: C++ standard does not specify what is going to happen in this case Clang and GCC seem to use C++ … Read more
Bug in the C++ standard library in std::poisson_distribution?
My system is set up as follows (Debian testing): libstdc++-7-dev: Installed: 7.2.0-16 libc++-dev: Installed: 3.5-2 clang: Installed: 1:3.8-37 g++: Installed: 4:7.2.0-1d1 I can confirm the bug when using libstdc++: g++ -o pois_gcc -std=c++11 pois.cpp clang++ -o pois_clang -std=c++11 -stdlib=libstdc++ pois.cpp clang++ -o pois_clang_libc -std=c++11 -stdlib=libc++ pois.cpp Result:
The reason of using `std::greater` for creating min heap via `priority_queue`
The logical argument is as follows std::priority_queue is a container adaptor; basic memory considerations make the back the preferred place for modifications (with pop_back() and push_back()) for sequence containers such as std::vector. the priority_queue primitives are based on std::make_heap (constructor), std::pop_heap + container::pop_back (priority_queue::pop) and on container::push_back + std::push_heap (priority_queue::push) pop_heap will take the front … Read more
Why Aren’t `std::uniform_int_distribution` and `std::uniform_int_distribution` Allowed?
There is a library working group unresolved[1] issue on this uniform_int_distribution<unsigned char> should be permitted and it says, amongst other things: I am not aware of anything in <random> that works with 16-bit integers but fails with 8-bit integers, so I suspect that IntType and UIntType could simply be extended to permit the char family. … Read more
Why isn’t std::array::size static?
Since C++11 you can use std::tuple_size on std::array to obtain the size as a compile time constant. See http://en.cppreference.com/w/cpp/container/array/tuple_size
Can I use template aliases as template template parameters?
Yes, it is apparently allowed. According to the latest draft of the upcoming standard I could find, it is stated that A template-argument for a template template-parameter shall be the name of a class template or an alias template […]. However, alias templates seems very seldomly supported at the moment, so you might have some … Read more