Recent questions tagged C++

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Let's say we have a 2D int array: int a[3][4] = { { 1,3,2,4 }, { 2,1,5,3 }, { 0,8 ... Can I absolutely treat 2D arrays as 1D arrays when needed? 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++ - Inserting a vector of unique_ptr into another vector

I have a vector of unique_ptr's and I want to append them to another vector of unique_ptrs. I would normally do a ... using gcc 4.8.1. 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++ - Visual Studio 2013 (vs120) asks for wrong boost libraries

I'm trying to compile one of my projects on Windows 7, using Visual Studio 2013. I've installed Boost 1 ... me understand what is happening? 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++ - SFINAE away a copy constructor

Under certain conditions, I'd like to SFINAE away the copy constructor and copy assignment operator of a class ... there exist a workaround? 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++ - Get millisecond part of time

I need to get milliseconds from the timer // get timer part time_t timer = time(NULL); struct tm now = * ... get %f for milliseconds from tm? 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++ - Serializing function objects

Is it possible to serialize and deserialize a std::function, a function object, or a closure in ... representation of functions 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++ - Does pointer arithmetic have uses outside of arrays?

I think I understand the semantics of pointer arithmetic fairly well, but I only ever see examples when dealing ... taking a difference, etc. 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++ - C++11 constexpr function's argument passed in template argument

This used to work some weeks ago: template <typename T, T t> T tfunc() { return t + 10; } template <typename ... (tags/RELEASE_30/final) (3.0.1) 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++ - Chaining Bool values give opposite result to expected

Unthinkingly I wrote some code to check that all the values of a struct were set to 0. To accomplish this I ... the code using VS9 and VS8. 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++ - Hiding instantiated templates in shared library created with g++

I have a file that contains the following: #include <map> class A {}; void doSomething() { std::map<int, A> m ... this just a omission in g++? 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++ - Return std::tuple and move semantics / copy elision

I have the following factory function: auto factory() -> std::tuple<bool, std::vector<int>> { std::vector<int ... ); Is it that really required? 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++ - Should I use virtual 'Initialize()' functions to initialize an object of my class?

I'm currently having a discussion with my teacher about class design and we came to the point of Initialize() ... make sense for them. Sorry. 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++ - multithread read from disk?

Suppose I need to read many distinct, independent chunks of data from the same file saved on disk. Is it ... multi-threading with OpenMP.) 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 this variadic argument count macro fail with VC++?

I got the following implementation to get the number of arguments in a variadic macro (currently limited to 16 ... help would be appreciated. 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 requires me to declare "using namespace std;"?

This question may be a duplicate, but I can't find a good answer. Short and simple, what requires me to ... namespace std; in C++ programs? 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++ - Division by zero does not throw SIGFPE

I have a small program performing floating-point division by zero, so I expect SIGFPE. #include <sys/types.h> ... type and so on)? 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++ - Qt 5, get the mouse position in a screen

First of all, I'd like to mention that I found that related post How to get the mouse position on ... and QDesktopWidget classes with no luck. 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++ - Have compiler check the number of array initializers

Initializing an array (in C++, but any solution which works for C will likely work here as well) with less ... trick won't work for 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++ - Why does abs(complex<int>) always return zero?

The following code with VS2010 prints 0, contrary to my expectations: #include <complex> #include <iostream> using ... the type is double. 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++ - no matching function for call to ' '

I was given to implement the function: "static double distanta (const Complex&, const Complex&);" which return the ... I'm doing wrong? 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++ - How to make QCheckBox readonly, but not grayed-out

Any good way to make a checkbox readonly, but also not grayed-out (hardly visible). I have used ... QCheckBox while retaining checked state? 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++ - Connect QML signal to C++11 lambda slot (Qt 5)

Connecting a QML signal to a regular C++ slot is easy: // QML Rectangle { signal foo(); } // C++ ... syntax for the QObject::connect call? 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 can I extend a compiler generated copy constructor

I frequently run into the problem, that I must extend a compiler generated copy constructor. Example: class xyz; ... possibility. Is there any? 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 HWND of current Process

I have a process in c++ in which I am using window API. I want to get the HWND of own process. Kindly guide me how can I make it possible. 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++ - Is left-shifting a signed integer undefined behavior in C++03?

According to C++03, 5.8/2, left-shifting is defined as follows: The value of E1 << E2 is E1 (interpreted ... a signed integer defined in C++03? 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++ - Is sizeof(size_t) == sizeof(void*) always true?

Does the C99/C++11 standard guarantee that sizeof(size_t) == sizeof(void*) is always true? size_t f(void* p) { return ... (n); // Is it safe? } 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 std::vector<bool> have no .data()?

The specialisation of std::vector<bool>, as specified in C++11 23.3.7/1, doesn't declare a data() member ... an array of bools not be returned? 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++ - Template specialization with variadic templates

template <size_t size, typename ...Params> void doStuff(Params...) { } template <> void doStuff<size_t ... How to specialize variadic templates? See Question&Answers more detail:os...

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

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