Recent questions tagged C++

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c++ - OpenMP set_num_threads() is not working

I am writing a parallel program using OpenMP in C++. I want to control the number of threads in the ... to control the number of threads? 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 reverse the order of arguments of a variadic template function?

I have a template function with varargs template arguments, like this template<typename Args...> void ascendingPrint(Args ... reverse(args) ); } 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 is decltype with two arguments?

Edit, in order to avoid confusion: decltype does not accept two arguments. See answers. The following two ... with one expression everywhere. 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 do I prevent a class from being allocated via the 'new' operator? (I'd like to ensure my RAII class is always allocated on the stack.)

I'd like to ensure my RAII class is always allocated on the stack. How do I prevent a class from being allocated via the 'new' operator? 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++ - Escape sequence f - form feed - what exactly is it?

f is said to be the form feed. is a tab, a is a beep, is a newline. What exactly is a form feed - f ... :) and then goodbye all on one line. 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++ - Compiling a static executable with CMake

for a project I need to create an executable that includes all the libraries that I used (opencv, cgal) in ... libraries? Can you help me? 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++ - Performance cost of passing by value vs. by reference or by pointer?

Let's consider an object foo (which may be an int, a double, a custom struct, a class, whatever). My ... than the other inside the function)? 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++ - Memory Allocation char* and char[]

What is the difference between these two in terms of memory allocation. char *p1 = "hello"; char p2[] = "hello"; 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++ - ampersand (&) at the end of variable etc

I am a C++ noob and i've a problem of understanding c++ syntax in a code. Now I am quite confused ... definitely need the variable name, right? 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++ - Rotate cv::Mat using cv::warpAffine offsets destination image

I'm trying to rotate a 1296x968 image by 90 degrees using the C++ API of OpenCV and I'm facing a few problems ... (orig_image, 90); return 0; } 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++ - Which <type_traits> cannot be implemented without compiler hooks?

C++11 provides standard <type_traits>. Which of them are impossible to implement without compiler hooks? Note 1: ... support (thanks sehe). 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++ - unordered_map thread safety

I am changing a single thread program into multi thread using boost:thread library. The program uses unordered_map as ... be a good option? 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++ - Which std::async implementations use thread pools?

One of the advantages of using std::async instead of manually creating std::thread objects is supposed to be ... any information you can offer. 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++ - Console output in a Qt GUI app?

I have a Qt GUI application running on Windows that allows command-line options to be passed and under some ... can get this to work? 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++ - Pure virtual functions may not have an inline definition. Why?

Pure virtual functions are those member functions that are virtual and have the pure-specifier ( = 0; ) Clause ... to mean lexically in-class 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 is going on with 'gets(stdin)' on the site coderbyte?

Coderbyte is an online coding challenge site (I found it just 2 minutes ago). The first C++ challenge you ... is irrelevant to my issue 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++ - Loop unrolling to achieve maximum throughput with Ivy Bridge and Haswell

I am computing eight dot products at once with AVX. In my current code I do something like this (before unrolling): ... &c[7*vec_size], tmp7); } 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++ - SetupDiGetDeviceProperty usage example

Can anybody provide me with an example of using SetupDiGetDeviceProperty ? 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++ - In C++11, does `i += ++i + 1` exhibit undefined behavior?

This question came up while I was reading (the answers to) So why is i = ++i + 1 well-defined in ... existence is only implicit in the standard. 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++ - MinGW linker error: winsock

I am using MinGW compiler on Windows to compile my C++ application with sockets. My command for linking looks ... the problem can be, please? See Question&Answers more detail:os...

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

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217 views

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c++ - What are the use cases for having a function return by const value for non-builtin type?

Recently I have read that it makes sense when returning by value from a function to qualify the return type ... returned object should be const? 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++ - std::map default value

Is there a way to specify the default value std::map's operator[] returns when an key does not exist? 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++ - SSE, intrinsics, and alignment

I've written a 3D vector class using a lot of SSE compiler intrinsics. Everything worked fine until I ... issues coming with SSE intrinsics? See Question&Answers more detail:os...

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

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298 views

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c++ - How to identify the file content as ASCII or binary

How do you identify the file content as being in ASCII or binary using C++? 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++ - Nonstatic member as a default argument of a nonstatic member function

struct X { X():mem(42){} void f(int param = mem) //ERROR { //do something } private: int mem; } ... can't understand why would this be illegal! See Question&Answers more detail:os...

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

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675 views

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c++ - CMake: include library dependencies in a static library

I am building a static library in CMake, which is dependent on many other static libraries. I would like ... this line for static libraries. See Question&Answers more detail:os...

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

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354 views

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c++ - C++11: Compile Time Calculation of Array

Suppose I have some constexpr function f: constexpr int f(int x) { ... } And I have some const int N known at compile ... << X[3] << endl; } 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 equivalent to boost shared_mutex

Is there a C++11 equivalent for the boost::shared_mutex. Or another solution to handle a multiple reader / single writer situation in C++11? See Question&Answers more detail:os...

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

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