Recent questions tagged c++

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c++ - Connecting IPv4 client to IPv6 server: connection refused

I am experimenting with IPv6 sockets, particularly the "dual stack" capability offered on Windows Vista and later, ... address. (emphasis mine)" 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::vector and copy constructors

vector<X> v; X x; v.push_back(x); v.push_back(x); v.push_back(x); Why this code calls the copy ... happens under hood with this particular STL. 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 Create a Gdiplus::Bitmap from an HBITMAP, retaining the alpha channel information?

When I create a new Gdiplus::Bitmap using the Bitmap::FromHBITMAP function, the resulting Bitmap is opaque - ... across the alpha channel data? 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++ - Tuple isn't being constructed in order?

The following program: #include <iostream> #include <tuple> struct A { A() { std::cout << "A constructor "; } }; struct B ... , A, B, ..., Y, Z? 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 use std::signaling_nan?

After looking at another question on SO (Using NaN in C++) I became curious about std::numeric_limits<double>:: ... when I get home. Thanks! 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 cross platform GUI library has the most native feel for each platform?

I've noticed that GTK has a uniform feel across all platforms, which is great for Linux lovers, but not so great for ... Qt is what I'm after? 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++ - Compilation problems with vector<auto_ptr<> >

Consider the following code: #include <iostream> #include <memory> #include <vector> using namespace std; struct A { ... t be used in vectors? 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 shortest circuit in a graph that visits X nodes at least once

Even though I'm still a beginner, I love solving graph related problems (shortest path, searches, etc). ... algorithm that could solve 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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c++ - How to implement a QThread that runs forever{} with a QWaitCondition but still needs to catch another Slot while doing that

I implemented a class that can write data to a serial port via a QQueue and read from it by a slot. I ... ; m_enqueueMessageMutex->unlock(); } } 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 destructor for union-like class

I'm trying to use an union (C++) that has some non-primitive variables, but I'm stuck trying to create ... be used without flaws and issues? 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 avoid data race with `asio::ip::tcp::iostream`?

My question How do I avoid a data race when using two threads to send and receive over an asio::ip::tcp::iostream? ... << "resetting "; } } } 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++ - ++it or it++ when iterating over a map?

Examples showing how to iterate over a std::map are often like that: MapType::const_iterator end = data.end(); for ( ... if I use it++ instead? 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++ - Different math rounding behaviour between Linux, Mac OS X and Windows

HI, I developed some mixed C/C++ code, with some intensive numerical calculations. When compiled in Linux ... optimizations) and specified -m32 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++ - Copy constructor curly braces initialization

"we can initializate objects of a class for which we have not define any constructor using: memberwise initialization. ... ?. Thanks in advance. 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 highlight the entire row on mouse hover in QTableWidget: Qt5

I want to highlight the row on mouse hover in my QTableWidget. When I hover the mouse, only single cell ... edited) row on mouse hover. See Question&Answers more detail:os...

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

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750 views

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c++ - How can I get the screen resolution using SDL2?

I'm using pixel-perfect source images and SDL2 to make a program. When set to fullscreen, I'd like it to ... solution than that. It feels dirty. See Question&Answers more detail:os...

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

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435 views

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c++ - How to pass an array size as a template with template type?

My compiler behaves oddly when I try to pass a fixed-size array to a template function. The code looks as ... are of type std::ptrdiff_t. See Question&Answers more detail:os...

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

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583 views

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c++ - Are there any use cases for a class which is copyable but not movable?

After reading this recent question by @Mehrdad on which classes should be made non-movable and therefore non-copyable, ... in the same class? 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 is this call to member function ambiguous?

Consider this class: class Base{ public: void func(double a) = delete; void func(int a) const {} }; int main ... ); Why is this code ambiguous ? 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 does chrono have its own namespace?

Everything else I have seen so far in the C++ standard library is in the std namespace. If I use things ... chrono header has its own namespace? See Question&Answers more detail:os...

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

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625 views

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c++ - Issue with std::reference_wrapper

The issue is clear with the following code: #include <functional> #include <iostream> #include <vector> int main( ... explain this to me? 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++ - Getting the error floating point exception: 8

I have no idea why g++ doesn't like my code. It ran fine in java. Any insights would be greatly appreciated. ... 0) return false; return true; } 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 Goto function across different functions

How can I use goto function across different functions .For ex , main() { .... REACH: ...... } void ... ; } How to implement such usage ? 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 support comparisons for QVariant objects containing a custom type?

According to the Qt documentation, QVariant::operator== does not work as one might expect if the variant ... a particular enumerated value. See Question&Answers more detail:os...

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

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534 views

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c++ - Boost Program Options Add Options Syntax

I am writing a program that uses Boost's Program Options library and I noticed the following syntax that has ... manipulate syntax like 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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842 views

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c++ - Can I move-assign a std::map's contents into another std::map?

Is it possible to insert the contents of a temporary std::map temp into another std::map m by using move ... into m, instead of copying? See Question&Answers more detail:os...

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

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517 views

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c++ - OpenGL two different 3d rendering picture control on single MFC dialog not working

I am making an application using VC++ MFC where i have two different opengl windows. I have followed the tutorial of ... -1.0f); glEnd(); } See Question&Answers more detail:os...

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

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895 views

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c++ - FreeImage: Get pixel color

I'm writing a little application that reads color of each pixel in image and writes it to file. First I did ... .htm. Thank you very much! See Question&Answers more detail:os...

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

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