Recent questions tagged C++

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c++ - Is cpu clock time returned by have to be exactly same among runs?

I have big project written in C++. It might have some stability problems (i.e. random runtime), but I'm ... it possible? Platform is Windows 7. 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 it legal to use placement new on initialised memory?

I am exploring the possibility of implementing true (partially) immutable data structures in C++. As C++ does not ... ++ using std::launder(). 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++ - Can I initialize a union in a mem-initializer?

I'm surprised this doesn't work: union DlDatum { float mFloat; s32 mInteger; }; class DlDbE { public: DlDbE( ... .. private: DlDatum mData; }; 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 value in unordered_map

I am using Boost unordered_map. I have a key value pair for each entry. How could I determine whether a particular ... and key as value) 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++ - <string.h> conflicting with my own String.h

I have a project that was compiling ok within g++(I can't see the version right now) and now on ... Any help is appreciated Thanks, Jonathan 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++ - A failure to instantiate function templates due to universal (forward) reference to a templated type

Universal references (i.e. "forward references", the c++ standard name) and perfect forwarding in c++ ... references with templated types? 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++ - Calling a non-exported function in a DLL

I have a program which loads DLLs and I need to call one of the non-exported functions it contains. Is ... and stuff for the functions. 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 blocks implementation of std::to_chars and std::from_chars

According to https://en.cppreference.com/w/cpp/compiler_support#cpp17, no major vendor yet supports floating point ... some more fancy stuff. 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 one need to call srand() C function per thread or per process to seed the randomizer?

The caption pretty much says it. PS. This is for C++ Windows program. 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++ - error: switch quantity not an integer

I have researched my issue all over StackOverflow and multi-google links, and I am still confused. I figured the ... , I appreciate your help. 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++ - Undefined reference, using FFMpeg-library (AvCodec) on Ubuntu, 64-bits system

I am running the example code of the latest FFMpeg-library. I have inserted the example code into the file ... running on a Windows-OS). 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++ - Calling virtual function of derived class from base class constructor?

I′m trying to accomplish the same which is described in a previous question: virtual function call from base ... -inheritance.html#faq-23.6 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++ - Sequencing of function parameter destruction

According to C++14 [expr.call]/4: The lifetime of a parameter ends when the function in which it is ... not use the standard sequencing terms? 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 C++0x's `noexcept` checked dynamically?

I am curious about the rationale behind noexcept in the C++0x FCD. throw(X) was deprecated, but noexcept ... functions within a try block. 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 assert(false) ignored in release mode?

I am using VC++. Is assert(false) ignored in release mode? 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 ={} initialization doesn't work for tuple?

To me a pair is just special case of a tuple, but following surprises me: pair<int, int> p1(1, 2); // ok tuple<int ... <int, int> t2={1, 2}; ^ 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++ - GCC: sorry, unimplemented: 64-bit mode not compiled in

I have built GCC 4.7 on my x86 32-bit linux system. When I try to cross-compile with the -m64 flag ... : 64-bit mode not compiled in 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 Smart Pointer Policies

As I understand it, in the current specification of C++11, one should use: std::unique_ptr<> for one ... > and auto_ptr<> effectively obsolete? 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++ - __int64 on a 32-Bit machine?

I just tried something in MSVC 2010 on my 32-bit machine here and found out that I can use __int64 in my ... work! How is that 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++ - Why is non-const std::array::operator[] not constexpr?

I'm trying to fill a 2D array on compile time with a given function. Here is my code: template<int H, int ... array, but cannot use std::array. 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++ - Optional Template parameter

Is it possible to have optional template parameter in C++ , for example template < class T, class U, class V> ... If Yes how to do 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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133 views

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c++ - Why does division by 3 require a rightshift (and other oddities) on x86?

I have the following C/C++ function: unsigned div3(unsigned x) { return x / 3; } When compiled using clang ... width and imul vs. mul.) 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++ - Add the installation prefix of "Qt5Widgets" to CMAKE_PREFIX_PATH

I don't know a lot about cmake, I'm trying to build a client using cmake and Qt. Getting the following error ... /user/Programs did not help 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++ - What is the order of destruction of function arguments?

If some function f with parameters p_1, ..., p_n of types T_1, ..., T_n respectively is called with ... on this question for the distinction. 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 the Nth type of variadic template templates?

How to get the Nth type of variadic template templates? For example template<typename... Args> class MyClass { Args[0] ... to get the type? }; See Question&Answers more detail:os...

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

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358 views

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c++ - Is unique_ptr thread safe?

Is unique_ptr thread safe? Is it impossible for the code below to print same number twice? #include <memory> #include < ... (); } return 0; } See Question&Answers more detail:os...

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

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179 views

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c++ - calling a global function with a class method with the same declaration

I would like to wrap a C library within a C++ class. For my C++ class I also would like to have the ... class function not the global one } } 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++ - When should I use [[maybe_unused]]?

What is good about using [[maybe_unused]]? Consider int winmain(int instance, int /*prevInstance*/, const char */* ... , but is it worth using? See Question&Answers more detail:os...

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

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