Recent questions tagged C++

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Ive almost only programmed in objective-c, for a couple of months ago I programmed a little in box2d and say this "- ... don't know what it is. See Question&Answers more detail:os...

asked Oct 24, 2021 in Technique[技术] by 深蓝 (71.8m points)

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c++ - How to generate the same random number sequence over multiple types of compilers and kernels with <random>?

The problem I need to produce the same (pseudo) random number sequence on different machines and compilers. If I ... welcomed but I prefer MT See Question&Answers more detail:os...

asked Oct 24, 2021 in Technique[技术] by 深蓝 (71.8m points)

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c++ - SFINAE and decltype(auto)

If a function template returns decltype(auto) (or another type specifier using auto) but the return statement ... fodder for another question. See Question&Answers more detail:os...

asked Oct 24, 2021 in Technique[技术] by 深蓝 (71.8m points)

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c++ - Does an exception use move semantics when thrown in C++11?

http://www.drdobbs.com/cpp/practical-c-error-handling-in-hybrid-env/197003350?pgno=4 In this article Herb Sutter ... 11 is this still necessary? See Question&Answers more detail:os...

asked Oct 24, 2021 in Technique[技术] by 深蓝 (71.8m points)

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c++ - Program with "noexcept" constructor accepted by gcc, rejected by clang

The code: struct T { T() {} }; struct S { T t; S() noexcept = default; }; int main() ... works based on is_constructible and similar traits. See Question&Answers more detail:os...

asked Oct 24, 2021 in Technique[技术] by 深蓝 (71.8m points)

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c++ - ternary operator of different types

The following piece of code behaves differently under g++ 4.9.2 and clang++ 3.7.0. Which one is correct? What ... ~ ~~~~~~ 1 error generated. See Question&Answers more detail:os...

asked Oct 24, 2021 in Technique[技术] by 深蓝 (71.8m points)

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c++ - Sorting std::unordered_map by key

How can I sort an unordered_map by key? I need to print an unordered_map sorted by key. See Question&Answers more detail:os...

asked Oct 24, 2021 in Technique[技术] by 深蓝 (71.8m points)

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c++ - How do I avoid name collision with macros defined in Windows header files?

I have some C++ code that includes a method called CreateDirectory(). Previously the code only used STL ... rename my CreateDirectory() method? See Question&Answers more detail:os...

asked Oct 24, 2021 in Technique[技术] by 深蓝 (71.8m points)

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c++ - Constexpr if alternative

I would like to use constexpr if to branch at compile time, but it does not seem to be supported by the ... is not supported by the compiler? See Question&Answers more detail:os...

asked Oct 24, 2021 in Technique[技术] by 深蓝 (71.8m points)

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c++ - Static or dynamic linking the CRT, MFC, ATL, etc

Back in the 90s when I first started out with MFC I used to dynamically link my apps and shipped the ... mainly STL/Boost nowadays FWIW. See Question&Answers more detail:os...

asked Oct 24, 2021 in Technique[技术] by 深蓝 (71.8m points)

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c++ - Are structs of variables of the same type layout compatible with a struct containing an array of that type?

Are these 2 structs layout-compatible? struct One { float x, y, z; }; struct Two { float c[3]; }; Both ... , that sizeof(One)==sizeof(Two)? See Question&Answers more detail:os...

asked Oct 24, 2021 in Technique[技术] by 深蓝 (71.8m points)

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c++ - Volatile and multithreading: is the following thread-safe?

Assume there are two threads running Thread1() and Thread2() respectively. The thread 1 just sets a global ... shared variable using a lock? See Question&Answers more detail:os...

asked Oct 24, 2021 in Technique[技术] by 深蓝 (71.8m points)

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c++ - std::is_constant_evaluated behavior

GCC9 already implements std::is_constant_evaluated. I played a little bit with it, and I realized it is somewhat tricky. ... or not. Am I right? See Question&Answers more detail:os...

asked Oct 24, 2021 in Technique[技术] by 深蓝 (71.8m points)

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c++ - Why do gcc and clang allow me to construct an abstract class?

The following code compiles on a wide range of gcc and clang versions - when compiled and run with gcc 5.3 ... with clang 3.2: Compiler Explorer See Question&Answers more detail:os...

asked Oct 24, 2021 in Technique[技术] by 深蓝 (71.8m points)

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c++ - What happens when you logical not a float?

I assume this just returns an int. Is there anything else going on I should be aware of? C/C++ differences? ... does this return? Int? Float? See Question&Answers more detail:os...

asked Oct 24, 2021 in Technique[技术] by 深蓝 (71.8m points)

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c++ - String concatenation using preprocessor

is it possible to concatenate strings during preprocessing? I found this example #define H "Hello " #define W " ... feature of c preprocessor? See Question&Answers more detail:os...

asked Oct 24, 2021 in Technique[技术] by 深蓝 (71.8m points)

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c++ - convert a console app to a windows app

(its a long story) but I have a large complex project file containing a windows program. Unfortunately the ... somewhere to make this change? See Question&Answers more detail:os...

asked Oct 24, 2021 in Technique[技术] by 深蓝 (71.8m points)

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c++ - Finding size of dynamically allocated array

Why is it not possible to get the length of a buffer allocated in this fashion. AType * pArr = new ... provided that will fetch the length? See Question&Answers more detail:os...

asked Oct 24, 2021 in Technique[技术] by 深蓝 (71.8m points)

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c++ - Using numeric_limits::max() in constant expressions

I would like to define inside a class a constant which value is the maximum possible int. Something like this: ... the error message? Thank you. See Question&Answers more detail:os...

asked Oct 24, 2021 in Technique[技术] by 深蓝 (71.8m points)

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c++ - Can std::array be used in a constexpr class?

I am currently creating a class with a constexpr constructor and I wonder if I can use an std::array to store ... be accessed at compile-time ? See Question&Answers more detail:os...

asked Oct 24, 2021 in Technique[技术] by 深蓝 (71.8m points)

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c++ - Switch statement using or

I'm creating a console app and using a switch statement to create a simple menu system. User input is in the ... don't want to repeat code. See Question&Answers more detail:os...

asked Oct 24, 2021 in Technique[技术] by 深蓝 (71.8m points)

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c++ - How to write a `for` loop over bool values (false and true)

A question mostly for fun/curiosity: how to write a for loop in C++ that would iterate over two ... select between continuing and exiting. See Question&Answers more detail:os...

asked Oct 24, 2021 in Technique[技术] by 深蓝 (71.8m points)

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c++ - Member template in local class

Given the following code: void f() { class A { template <typename T> void g() {} }; } g++ ... declaration cannot appear at block scope". See Question&Answers more detail:os...

asked Oct 24, 2021 in Technique[技术] by 深蓝 (71.8m points)

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c++ - OpenMP: are local variables automatically private?

#pragma omp parallel { int x; // private to each thread ? } #pragma omp parallel for for (int i = 0; i ... is the point of using private clause? See Question&Answers more detail:os...

asked Oct 24, 2021 in Technique[技术] by 深蓝 (71.8m points)

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c++ - What does the integer suffix J mean?

I have the following source: int main() { 000J; } With gcc 4.8.4 it compiles without errors. I know there are ... about J. So what does it do? See Question&Answers more detail:os...

asked Oct 24, 2021 in Technique[技术] by 深蓝 (71.8m points)

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c++ - Multithreading for image processing at GPU using CUDA

Problem Statement: I have to continuously process 8 megapixel images captured from a camera . There have to be ... steps and proper logic. See Question&Answers more detail:os...

asked Oct 24, 2021 in Technique[技术] by 深蓝 (71.8m points)

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c++ - Why do we need .lib file in case of importing functions from .dll?

Can you help me to understand, why do we need .lib files when importing functions and data from dll? I've ... why does it really needs them? See Question&Answers more detail:os...

asked Oct 24, 2021 in Technique[技术] by 深蓝 (71.8m points)

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c++ - Efficient SSE NxN matrix multiplication

I'm trying to implement SSE version of large matrix by matrix multiplication. I'm looking for an efficient ... how to start implementing this. See Question&Answers more detail:os...

asked Oct 24, 2021 in Technique[技术] by 深蓝 (71.8m points)

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