Recent questions tagged C++

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c++ - QT - Specify DLL path in pro. file

So as the question title says, i'm specifically wondering how to include the path to a .dll file in the actually ... advance for 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++ - Access protected member of a class in a derived class

i have an old codebase here, where they used protected member variables. Whether or not this is a good idea can be ... ); Why is that the case? 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++ - If changing a const object is undefined behavior then how do constructors and destructors operate with write access?

C++ standard says that modifying an object originally declared const is undefined behavior. But then how do ... according to the standard? 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 there a way to print an Armadillo matrix in gdb?

I'm using gdb to debug my c++ program. I'm using the armadillo numerical library to define my matrices. ... matrix while using the gdb debugger? 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 Effect Would LWG2349 Have?

While libstdc++ does not, libc++ does follow the standard which states that passing ios_base::failbit to ... from throwing any errors? 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++ - Difference between Ranges algorithms and std algorithms

Many standard library algorithms have two versions in C++20: one in the std namespace and another one in ... two versions of these algorithms? 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 C# use the -> pointer notation?

I am trying to learn C# and I am familiar with the C++ struct pointing notation ->. I was curious if ... : someStruct->someAttribute += 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++ - enable_shared_from_this (c++0x): what am I doing wrong?

I'm just toying around with the smart pointers in the upcoming new c++ standard. However I fail to grasp the ... how can I know this beforehand? 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++ - Passing function objects into std algorithms by reference

Isn't it better to pass function objects into the STL algorithms by forwarding reference rather then by value? ... w/o wrapping them. 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 switch a process between default desktop and Winlogon desktop?

I am writing a remote desktop application like TeamViewer in C++ on Windows 7 (x64) and Windows 8 (x64) ... process running under winlogon.exe. 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 GCC rejects std::optional for references?

std::optional<int&> xx; just doesn't compile for the latest gcc-7.0.0 snapshot. Does the C++17 standard ... whould cause no problems i guess.) 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++ - QWebEngine: print a page?

The migration from QWebKit to QWebEngine seems to be much more complicated than Qt guys claimed. With QWebKit I ... a page using QWebEngine? 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++ - Static initialization order fiasco

In his "Thinking in C++" (Chapter 10) Eckel describes a technique that was pioneered by Jerry Schwarz to ... breaking down the whole technique. 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++ - new of incomplete type compiles when wrapped in template

Consider this code, with an obvious compile error: (1) struct A; struct B { B() { new A(); } // error: allocation of ... +-3.5.0 and g++-4.9.2 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++ - Why are redundant class name qualifiers allowed?

I came across some code like this: struct A { A() {} A(int) {} }; struct B : A { void init( ... way to prevent this construct from being used? 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++ - libc++ - stop std renaming to std::__1?

After substantial effort getting clang and libc++ to compile, run, integrate with NetBeans, and even cross- ... x86/CoreCache.o CoreCache.cpp 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++ - Dependent name lookup in function template: clang rejects, gcc accepts

Consider the following fragment: struct X { }; namespace foo { template <class T> void bar() { T{} < T{}; } ... gcc bug or is this a clang bug? 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 make this variadic template code shorter using features from C++14 and C++1z?

This is a code snippet that I am going to use in order to check whether the variadic template types are unique ... versions of Clang and GCC. 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++ - Conditions for copy elision?

I wanted to verify the if the following optimizations work as expected: RVO Named RVO Copy elision when ... without defining copy constructors? 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++ - Do unrestricted unions require placement new and a constructor definition?

The examples I've seen of unrestricted unions always seem to use placement new when constructing. The Wikipedia ... states it's 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++ - How to insert a duplicate element into a vector?

I'm trying to insert a copy of an existing vector element to double it up. The following code worked in ... Is there something I'm missing? See Question&Answers more detail:os...

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

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432 views

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c++ - Missing const_iterator overload of std::vector::erase() with g++ 4.8

The following example will not compile using g++ 4.8.2: #include <iostream> #include <vector> using namespace ... I must use a const_iterator? 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 put std::string into boost::lockfree::queue (or alternative)?

I'm trying to put std::strings into boost::lockfree::queues so that my threads can update each other with new ... into a boost::lockfree::queue. 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++ - In which access control context are evaluated concepts?

This question is a follow up to this one [temp.concept]/5 says: A concept is not instantiated ([temp.spec]). [ ... , but b2 and b2_rec are 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++ - "undefined reference" to static member of template class accessed from static method

I have a static class method that needs access to a pointer MyTypePointer that therefore has to be declared static. ... } 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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442 views

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c++ - “no match for 'operator<'” when trying to insert to a std::set

I'm using gcc 4.3.3 to try to compile the following code: struct testStruct { int x; int y; bool operator< ... . What am I doing wrong here? 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 args[0] guaranteed to be the path of execution?

This is a fundamental question, but an important one none the less... When starting a C++ program whose main method ... but may port later on.)? See Question&Answers more detail:os...

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

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196 views

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c++ - std::array alignment

Trying out std::tr1::array on a mac i'm getting 16 byte alignment. sizeof(int) = 4; sizeof( std::tr1::array< int,3 ... T, N> ) = sizeof( T )*N See Question&Answers more detail:os...

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

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