Recent questions tagged C++

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c++ - constexpr vs. static const: Which one to prefer?

For defining compile-time constants of integral types like the following (at function and class scope), which ... question for that here. See Question&Answers more detail:os...

asked Oct 17, 2021 in Technique[技术] by 深蓝 (71.8m points)

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c++ - cmath vs math.h (And similar c-prefixed vs .h extension headers)

I've seen some information about differences between things like iostream vs iostream.h. From what I gathered ... more differences between them? See Question&Answers more detail:os...

asked Oct 17, 2021 in Technique[技术] by 深蓝 (71.8m points)

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c++ - What's the difference between span and array_view in the gsl library?

In several recent conference presentation I've heard Bjarne Stroustrup and others mention new coding guidelines for C+ ... supposed to be about. See Question&Answers more detail:os...

asked Oct 17, 2021 in Technique[技术] by 深蓝 (71.8m points)

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c++ - C++11 emplace_back on vector<struct>?

Consider the following program: #include <string> #include <vector> using namespace std; struct T { int a; ... tried single and double braces) See Question&Answers more detail:os...

asked Oct 17, 2021 in Technique[技术] by 深蓝 (71.8m points)

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c++ - C preprocessor macro specialisation based on an argument

Is it possible to have one macro expanded differently for one specific argument value and differently for all other ... If not, to nothing. See Question&Answers more detail:os...

asked Oct 17, 2021 in Technique[技术] by 深蓝 (71.8m points)

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167 views

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c++ - thread safety of MPI send using threads created with std::async

According to this website, the usage of MPI::COMM_WORLD.Send(...) is thread safe. However in my application I ... threads created by std::async? See Question&Answers more detail:os...

asked Oct 17, 2021 in Technique[技术] by 深蓝 (71.8m points)

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c++ - How to calculate perspective transform for OpenCV from rotation angles?

I want to calculate perspective transform (a matrix for warpPerspective function) starting from angles of rotation and ... works so strange? See Question&Answers more detail:os...

asked Oct 17, 2021 in Technique[技术] by 深蓝 (71.8m points)

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c++ - Why "universal references" have the same syntax as rvalue references?

I just made some research about those (quite) new features and I wonder why C++ Committee decided to ... Can anyone explain Committee decision? See Question&Answers more detail:os...

asked Oct 17, 2021 in Technique[技术] by 深蓝 (71.8m points)

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c++ - Generating one class member per variadic template argument

I have a template class where each template argument stands for one type of value the internal computation can handle ... . Thanks for any help! See Question&Answers more detail:os...

asked Oct 17, 2021 in Technique[技术] by 深蓝 (71.8m points)

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c++ - Ad hoc polymorphism and heterogeneous containers with value semantics

I have a number of unrelated types that all support the same operations through overloaded free functions (ad hoc ... possible? If so, how? See Question&Answers more detail:os...

asked Oct 17, 2021 in Technique[技术] by 深蓝 (71.8m points)

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166 views

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c++ - Should I use public or private variables?

I am doing a large project for the first time. I have lots of classes and some of them have public variables, ... in the real world and why? See Question&Answers more detail:os...

asked Oct 17, 2021 in Technique[技术] by 深蓝 (71.8m points)

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c++ - When and why would you use static with constexpr?

As a disclaimer, I have done my research on this before asking. I found a similar SO question but the answer ... if they can be used together? See Question&Answers more detail:os...

asked Oct 17, 2021 in Technique[技术] by 深蓝 (71.8m points)

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225 views

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c++ - Conversion from boost::shared_ptr to std::shared_ptr?

I got a library that internally uses Boost's version of shared_ptr and exposes only those. For my application, I'd ... version take care of it? See Question&Answers more detail:os...

asked Oct 17, 2021 in Technique[技术] by 深蓝 (71.8m points)

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455 views

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c++ - how to assign multiple values into a struct at once?

I can do this on initialization for a struct Foo: Foo foo = {bunch, of, things, initialized}; but, I can't do this ... c = 3; //... ad infinitum See Question&Answers more detail:os...

asked Oct 17, 2021 in Technique[技术] by 深蓝 (71.8m points)

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333 views

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c++ - How to perform atomic operations on Linux that work on x86, arm, GCC and icc?

Every Modern OS provides today some atomic operations: Windows has Interlocked* API FreeBSD has <machine/atomic. ... that supports CAS. See Question&Answers more detail:os...

asked Oct 17, 2021 in Technique[技术] by 深蓝 (71.8m points)

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223 views

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c++ - Can using a lambda in header files violate the ODR?

Can the following be written in a header file: inline void f () { std::function<void ()> func = [] {}; ... one constructor is in a header file? See Question&Answers more detail:os...

asked Oct 17, 2021 in Technique[技术] by 深蓝 (71.8m points)

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316 views

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c++ - Why should I initialize member variables in the order they're declared in?

I was writing some code today and got a weird compile error, which seems to be caused by initializing ... initializing member variables matter? See Question&Answers more detail:os...

asked Oct 17, 2021 in Technique[技术] by 深蓝 (71.8m points)

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111 views

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c++ - Getting a directory name from a filename

I have a filename (C:folderfoo.txt) and I need to retrieve the folder name (C:folder) in unmanaged C++. ... extract the path from the filename? See Question&Answers more detail:os...

asked Oct 17, 2021 in Technique[技术] by 深蓝 (71.8m points)

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75 views

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c++ - Loading a dll from a dll?

What's the best way for loading a dll from a dll ? My problem is I can't load a dll on process_attach, ... call a non-dllmain function, too. See Question&Answers more detail:os...

asked Oct 17, 2021 in Technique[技术] by 深蓝 (71.8m points)

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299 views

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c++ - Cmake include_directories()

asked Oct 17, 2021 in Technique[技术] by 深蓝 (71.8m points)

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235 views

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c++ - Should I delete the move constructor and the move assignment of a smart pointer?

I'm implementing a simple smart pointer, which basically keeps track of the number of references to a pointer ... ; } #endif // SMART_PTR_H_ See Question&Answers more detail:os...

asked Oct 17, 2021 in Technique[技术] by 深蓝 (71.8m points)

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85 views

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c++ - Deterministic builds under Windows

The ultimate goal is comparing 2 binaries built from exact same source in exact same environment and being ... Compare section in documentation. See Question&Answers more detail:os...

asked Oct 17, 2021 in Technique[技术] by 深蓝 (71.8m points)

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184 views

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c++ - Checking if two cubic Bézier curves intersect

For a personal project, I'd need to find out if two cubic Bézier curves intersect. I don't need to ... if two cubic Bézier curves intersect? See Question&Answers more detail:os...

asked Oct 17, 2021 in Technique[技术] by 深蓝 (71.8m points)

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98 views

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c++ - How can I write a stateful allocator in C++11, given requirements on copy construction?

As far as I can tell, the requirements on an allocator to be used with STL containers are laid out in ... it just an infrequently used feature? See Question&Answers more detail:os...

asked Oct 17, 2021 in Technique[技术] by 深蓝 (71.8m points)

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222 views

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c++ - Can nullptr be emulated in gcc?

I saw that nullptr was implemented in Visual Studio 2010. I like the concept and want to start using it as soon ... just to show what I mean.) See Question&Answers more detail:os...

asked Oct 17, 2021 in Technique[技术] by 深蓝 (71.8m points)

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193 views

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c++ - How to use new std::byte type in places where old-style unsigned char is needed?

std::byte is a new type in C++17 which is made as enum class byte : unsigned char. This makes impossible to ... how to use it in old places? See Question&Answers more detail:os...

asked Oct 17, 2021 in Technique[技术] by 深蓝 (71.8m points)

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722 views

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c++ - constexpr const vs constexpr variables?

It seems obvious that constexpr implies const and thus it is common to see: constexpr int foo = 42; // ... const and constexpr really the same? See Question&Answers more detail:os...

asked Oct 17, 2021 in Technique[技术] by 深蓝 (71.8m points)

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686 views

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c++ - Why do some people prefer "T const&" over "const T&"?

So, I realize that const T& and T const& are identical and both mean a reference to a const T. In ... they might strive for consistency. See Question&Answers more detail:os...

asked Oct 17, 2021 in Technique[技术] by 深蓝 (71.8m points)

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