Recent questions tagged C++

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I have followed the following step by step guide and I've managed, after a bit of fiddling, to get clang ... help would be appreciated. Thanks. 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++ - Usage of std::forward vs std::move

I always read that std::forward is only for use with template parameters. However, I was asking myself why. See the ... = std::forward(image); } 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++ - Template function inside template class

I have this code: template <class T> class MyClass { public: template <class U> void foo() { U a; a. ... do this? What is the right syntax? 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 detect region of large # of white pixels using OpenCV?

I want to detect a logo inside an image in order to remove it. I have an idea which is to look for ... to detect object of large pixels number. 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++ - lower_bound == upper_bound

What does lower_bound mean. If I had to guess I would answer that this function returns the iterator at the ... sorry for this confusion :-( 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 the angle from rotation matrix

I am using two image of the single object the object is roated certain degree from its first image. I have ... fixed only the object is moving. 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++ - Optimizations for pow() with const non-integer exponent?

I have hot spots in my code where I'm doing pow() taking up around 10-20% of my execution time. My input ... . Is it possible to do better? 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 update GCC in MinGW on Windows?

I'm used to manually install GCC from source before on Ubuntu and it was a painful process. So I really don' ... before can share me some tips? 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++ - Getting a boost::shared_ptr for this

I am making extensive use of boost:shared_ptr in my code. In fact, most of the objects that are allocated on ... counting my only option 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++ - What is *.o file?

I'm compiling own project. And it halted by this error: LINK||fatal error LNK1181: cannot open input file 'objwin ... missing. What do they do? 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++ - iterator for 2d vector

How to create iterator/s for 2d vector (a vector of vectors)? 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++ - Large 2D array gives segmentation fault

I am writing some C++ code in Linux where I have declared a few 2D arrays like so: double x[5000][ ... I protect myself against this problem? 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++ - Copying std::vector: prefer assignment or std::copy?

I have two vectors: std::vector<int> v1, v2; // Filling v1 ... And now I need to copy v1 to v2. Is there ... ), v2.begin()); (or vice versa)? 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++ - Do polymorphism or conditionals promote better design?

I recently stumbled across this entry in the google testing blog about guidelines for writing more testable code. ... by this testing guideline? 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++ - Recursive lambda functions in C++14

There is an oft-repeated 'trick' to write recursive lambda functions in C++11 that goes as follows: std:: ... a way to address those issues? 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++ - Should all/most setter functions in C++11 be written as function templates accepting universal references?

Consider a class X with N member variables, each of some copiable and movable type, and N corresponding ... references whenever possible"? 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 create/read/write JSON files in Qt5

Qt5 has a new JSON parser and I want to use it. The problem is that it isn't too clear about what the ... in Qt5 and what "encapsulates" 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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c++ integer->std::string conversion. Simple function?

Problem: I have an integer; this integer needs to be converted to a stl::string type. In the past, I've ... converting integer to string 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++ - const char* concatenation

I need to concatenate two const chars like these: const char *one = "Hello "; const char *two = "World"; ... 't simply use std::string instead. 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 forward declare a template class in namespace std?

#ifndef __TEST__ #define __TEST__ namespace std { template<typename T> class list; } template<typename T> void Pop( ... it out with the pointer. 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++ - shared_ptr: horrible speed

When comparing two variants of pointers—classic vs. shared_ptr—I was surprised by a significant increase of the ... std::shared_ptr <HalfEdge> e23; std::shared_ptr &lt...

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

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c++ - LRU implementation in production code

I have some C++ code where I need to implement cache replacement using LRU technique. So far I know two ... Are their any other better methods? 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++ standard practice: virtual interface classes vs. templates

I have to make a decision regarding generalization vs polymorphism. Well the scenario is standard: I want to make my ... hopes on you guys :) 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 boost::variant and boost::any work?

How do variant and any from the boost library work internally? In a project I am working on, I currently ... these classes before using 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++ - opengl: glFlush() vs. glFinish()

I'm having trouble distinguishing the practical difference between calling glFlush() and glFinish(). The docs say that ... ); render_stuff(); } 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++ - Does C++11 unique_ptr and shared_ptr able to convert to each other's type?

Does C++11 standard library provide any utility to convert from a std::shared_ptr to std::unique_ptr, or vice versa? Is this safe operation? 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 do we require requires requires?

One of the corners of C++20 concepts is that there are certain situations in which you have to write requires ... that the grammar requires 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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c++ - Creating JSON arrays in Boost using Property Trees

I'm trying to create a JSON array using boost property trees. The documentation says: "JSON arrays are mapped ... figure out. Can anyone 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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