Recent questions tagged C++

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I'm trying to write a wrapper synchronous method around async_read to allow non blocking reads on a socket. ... and correct during testing. 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++ - Objects of different classes in a single vector?

In my code, I have a set of objects: class Sphere { ... class Plane { ... ... And I need to ... add objects of different classes to a vector? 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++ - Array decay to pointers in templates

Please consider this code: #include <iostream> template<typename T> void f(T x) { std::cout << sizeof(T) << ... [27]? Besides using std::vector? 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 use MS code coverage tool in command line?

I have the following C++ code. #include <iostream> using namespace std; int testfunction(int input) { if ( ... the instructions in this post. 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 construct or return the underlying deque from a stack?

I want to be able to convert a std::stack<> to a std::deque<>. Is there a straightforward conversion? 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 formally guarantees that non-atomic variables can't see out-of-thin-air values and create a data race like atomic relaxed theoretically can?

This is a question about the formal guarantees of the C++ standard. The standard points out that the rules for std ... that lead to a data-race? 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 would you benchmark the performance of a function?

Here's perhaps a more advanced question. If you have two functions that return a value, int F(int input1 ... operations in the benchmark setup? 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++ - Copy object - keep polymorphism

The following code tries to copy an object and keep the original type. Unfortunately it does not work (every copied object ... // # I'm Super! 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++ - Boost interprocess mutexes and checking for abandonment

I have a need for interprocess synchronization around a piece of hardware. Because this code will need to work on ... Studio 2010. Thanks, Andy 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++ - stack growth direction

So from my previous memmove question I would like to know how to find direction of stack growth. void ... 1; stackDirtection(&i); } 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++ - Ruby win32 api interface

I need to access a few functions of the win32 library in ruby. I have found extremely sparse information on the ... module in C++? 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++ - How can I safely (and easily) count *all* instances of a class within my program?

I would like to be able to instantiate a particular (and otherwise normal) class (the source of which ... other operators for example? 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 are iostreams not copyable?

It's possible to make a local copy of an iostream object, using rdbuf and copyfmt. This allows formatting ... were designed as non-copyable? 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 time_t to int

I want to convert a given time into epoch(time_t) and vice versa. can anyone tell what is the routine or ... return 32399 for some reason. 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 assignment operator overloading mystery

I have a simple struct Wrapper, distinguished by two templated assignment operator overloads: template<typename T ... copy assignment 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++ - How to find an object with specific field values in a std::set?

I call a method which returns std::set<T> const& where T is a class type. What I'm trying to achieve is to ... be OK. How would you do that? 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++ - What is the fastest way to compute large power of 2 modulo a number

For 1 <= N <= 1000000000, I need to compute 2N mod 1000000007, and it must be really fast! My current approach ... to be fast enough. Any idea? 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++ - partial specialization ordering with non-deduced context

According to [temp.class.order] §14.5.5.2, the selection of a partial specialization of t in this ... implementations have the same bug? See Question&Answers more detail:os...

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

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176 views

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c++ - Pass by reference more expensive than pass by value

Is there a case where pass-by-reference is more expensive than pass-by-value in C++? If so, what would that case be? 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++ - array[byte] to HBITMAP or CBitmap

I have an array of bytes (which I read through a stream directly from a .bmp and then store as a BLOB in ... all that information is a bad idea. 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++ - FindWindow does not find the a window

I have a plan for make a simple trainer console with C++ but first step I've got problem with FindWindow() ... I hope anyone can 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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491 views

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c++ - Could we use extern "C" in C file without #ifdef __cplusplus?

Why shouldn't extern "C" be specified for a function that needs to be defined as a C function? What ... hence the #ifdef __cplusplus checking. See Question&Answers more detail:os...

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

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239 views

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c++ - How boost auto-linking makes choice?

When I use Visual Studio 2012, with auto-linking, I don't need to add boost / POCO/ python libraries manually, ... I just don't understand why? See Question&Answers more detail:os...

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

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308 views

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c++ - copy constructor of derived QT class

I have a class which is publicly inherited from QWidget: class MyWidget : public QWidget { Q_OBJECT public: MyWidget( ... what I am doing wrong. 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 happens when calling the destructor of a thread object that has a condition variable waiting?

I am using a SynchronisedQueue to communicate between threads. I found that destroying the thread object when the ... program. 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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560 views

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c++ - Emplace an aggregate in std::vector

I tried to initialize the std::vector std::vector<Particle> particles; with instances of the simple struct struct ... How can I fix that? See Question&Answers more detail:os...

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

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124 views

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c++ - How to invoke pointer to member function when it's a class data member?

struct B { void (B::*pf)(int, int); // data member B () : pf(&B::foo) {} void foo (int i, int j) { cout<<"foo( ... , e.g. (... ->* pf) (...)' 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 get content of web-page

i'm trying to get web-page data in string that than i could parse it. I didn't found any methods in qwebview, ... get(*request); Any results =(. See Question&Answers more detail:os...

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

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