Recent questions tagged C++

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c++ - Does std::atomic<std::string> work appropriately?

I am reading through Anthony Williams' "C++ Concurrency in Action" and in Chapter 5, which talks about the ... as expected? Thanks in advance! 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 I return std::strings?

I'm trying to use std::string instead of char* whenever possible, but I worry I may be degrading performance ... or const char*? 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++ - Will consteval functions allow template parameters dependent on function arguments?

In C++17, this code is illegal: constexpr int foo(int i) { return std::integral_constant<int, i>::value; ... integral_constant<int, i>::value; } 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++ sizeof( string )

#include <cstdlib> #include <iostream> int main(int argc, char *argv[]) { cout << "size of String " << ... , string can only hold 4 characters? 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 can I enumerate/list all installed applications in Windows XP?

When I say "installed application", I basically mean any application visible in [Control Panel]->[Add/Remove Programs]. ... C++ is also fine. 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++ - difference between pointer to an array and pointer to the first element of an array

int (*arr)[5] means arr is a pointer-to-an-array of 5 integers. Now what exactly is this pointer? Is it ... exactly is a pointer-to-an-array? 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++ - Converting a row of cv::Mat to std::vector

I have a fairly simple question: how to take one row of cv::Mat and get all the data in std::vector? The cv ... than a for loop for each row. 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 can I resize a 2D vector of objects given the width and height?

My class, GameBoard, has a member variable that is a 2D vector of an object of the class Tile. The GameBoard ... (iWidth,Tile(' ')); } 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++ - FindChessboardCorners cannot detect chessboard on very large images by long focal length lens

I can use FindChessboardCorners functions for images that less than 15 Mega pixel such like 2k x 1.5k. ... using at the correct resolution. 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++ - Multiple inheritance + virtual function mess

I have a diamond multiple inheritance scenario like this: A / B C / D The common parent, A, defines ... other means that virtual functions? 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 build a compile-time key/value store?

I have a problem where I need to map an integer at compile time to another integer. Basically, I need the compile- ... std::endl; 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++ - Is it possible to use threads to speed up file reading?

I want to read a file as fast as possible (40k lines) [Edit : the rest is obsolete]. Edit: ... Thanks aforehand. Sincerely, Mister mystère. 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 declare and define global variables in order to access them from all headers/source files properly

Well, I'm learning C++ and never really learned how to do stuff that is not OO. I'm trying to get a bit ... . How can I work around the 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++ - OpenCV groupRectangles - getting grouped and ungrouped rectangles

I'm using OpenCV and want to group together rectangles that have significant overlap. I've tried using groupRectangles ... way to achieve this? 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++ - Is returning with `std::move` sensible in the case of multiple return statements?

I'm aware that it's normally not a good idea to return with std::move, i.e. bigObject foo() { ... prepare_object(result); } return result; } See Question&Answers more detail:os...

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

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112 views

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c++ - Difference between string.h and cstring?

What is the difference between string.h and cstring? Which one should be used for C and which one for C++ (if at all)? 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 don't std::vector's elements need a default constructor?

And how can I write my own array class to not need a default constructor for its elements? Right now, when I do ... . How do they do this magic? 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++ - Using condition variable in a producer-consumer situation

I'm trying to learn about condition variables and how to use it in a producer-consumer situation. I have a queue ... } condQ.notify_one(); } } 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++ - linking problem: fatal error LNK1112: module machine type 'x64' conflicts with target machine type 'X86'

Im trying to run sample app from wxFreeChart library. After compilation on linking there is an error: ... ? thanks for 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++ - GCC error: explicit specialization in non-namespace scope

I am trying to port the following code. I know the standard doesn't allow explicit specialization in non-namescape ... { return false; } }; See Question&Answers more detail:os...

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

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131 views

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c++ - calling constructor of a class member in constructor

Can I call constructor of a member in my Class's constructor? let say If I have a member bar ... members in composition(aggregation). See Question&Answers more detail:os...

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

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152 views

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c++ - Weird undefined symbols of static constants inside a struct/class

Either I'm very tired or something weird is happening that I'm not aware of, because the code below is ... someone explain what's happening? 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++ - Is the typedef-name optional in a typedef declaration?

I was quite surprised when I saw the following code compile without errors or warnings in g++-4.2: ... declaration requires a typedef name" 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++ - Is it defined behavior to reference an early member from a later member expression during aggregate initialization?

Consider the following: struct mystruct { int i; int j; }; int main(int argc, char* argv[]) { ... behavior) with a user-defined constructor? 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++ - CMake and MsVS-NuGet

I'm currently developing a desktop application, using the C++ REST SDK (codename Casablanca), Qt5 and some other ... isn't really an 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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95 views

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c++ - Why does int main() {} compile?

(I'm using Visual C++ 2008) I've always heard that main() is required to return an integer, but here I didn't ... Could this be a bug in VC++? See Question&Answers more detail:os...

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

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674 views

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c++ - std::this_thread::sleep_for() and GCC

When I try to compile this simple program: #include<thread> void f() { std::this_thread::sleep_for(std::chrono: ... using a ready-made package. See Question&Answers more detail:os...

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

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359 views

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c++ - How to prevent non-specialized template instantiation?

I have a templated class (call it Foo) which has several specializations. I would like the compilation to fail if ... before ? I can use boost. See Question&Answers more detail:os...

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

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