I'm working in some code using the Curiously Recurring Template Pattern, where the derived class is passed up to specialize its own base classes at compile time. With this, I run into an annoying problem which I have made a toy example for. I have annotated base::bar with comments describing the expected behavior (and why I expect it). The entire example is intended to be compiled as is,
我正在使用Curiously Recurring Template Pattern进行一些代码工作，其中派生类在编译时传递给它自己的基类。 有了这个，我遇到了一个令人讨厌的问题，我已经做出了一个玩具的例子。 我用注释描述了预期行为（以及为什么期望它）注释了base :: bar。 整个示例旨在按原样进行编译，并导致3个编译器错误（clang-3.9），如注释中所述。 作为参考，$ 4.11 / 2： 可以将“类型cv T的B的成员的指针”的类型值（其中B是类类型）转
I wonder why a simple conversion from a derived class pointer to the base class pointer fails in the case of the pointer-to-member conversion. For example, struct Base {}; struct Derived: public Base {}; struct X { Derived field; }; int main(int argc, char *argv[]) { Base X::* ptr1 = &X::field; return 0; } Gives the error: $ g++ t.cc t.cc: In fu
我想知道为什么在指针到成员转换的情况下，从派生类指针到基类指针的简单转换失败。 例如， struct Base {}; struct Derived: public Base {}; struct X { Derived field; }; int main(int argc, char *argv[]) { Base X::* ptr1 = &X::field; return 0; } 给出错误： $ g++ t.cc t.cc: In function ‘int main(int, char**)’: t.cc:9:24: error: invalid conversion from ‘D
If conversion from pointer to Base member To pointer to Derived class member is valid, why does the following code fails to compile class Base { public: virtual void fun1() { cout<<"fun1 in Base"<<endl; } }; class Der { public: void fun1() { cout<<"fun1 in Der"<<endl; } }; int main() { void (Der::*funptr)() = &Base::fun1;
如果从指针转换为基本成员指向派生类成员的指针是有效的，为什么下面的代码无法编译 class Base { public: virtual void fun1() { cout<<"fun1 in Base"<<endl; } }; class Der { public: void fun1() { cout<<"fun1 in Der"<<endl; } }; int main() { void (Der::*funptr)() = &Base::fun1; } 编译器给出一个错误说 错误：无法在初始化|中将
I'm a little bit confused concerning virtual functions. Lets suppose you have Base class with virtual function foo(), and that function then overridden in Derived class class Baseclass { public: virtual void foo() { //... } }; class Derived: public BaseClass { private: int member_val; public: Derived( int init )
我对虚拟功能有点困惑。 让我们假设你有一个虚函数foo（）的Base类，然后该函数在Derived类中重写 class Baseclass { public: virtual void foo() { //... } }; class Derived: public BaseClass { private: int member_val; public: Derived( int init ) : member_val( init ) {} void foo() { member
I just found the following paragraphs in c++03 standard draft relevant to pointer to member conversion. 4.11/2 Pointer to member conversions An rvalue of type “pointer to member of B of type cv T,” where B is a class type, can be converted to an rvalue of type “pointer to member of D of type cv T,” where D is a derived class (clause 10) of B. If B is an inaccessible (clause 11), ambiguous (10
我刚刚在与指向成员转换的c ++ 03标准草案中找到以下段落。 4.11 / 2指向成员转换的指针 类型“cv T的B成员的指针”类型的右值，其中B是类类型，可以被转换为类型“指向c类型T的D的成员的指针”的右值，其中D是派生类（如果B是不可访问的（第11章），不明确的（10.2）或虚拟（10.1）D的基类，则需要此转换的程序是不合格的。 转换的结果与转换发生之前指向成员的指针指向相同的成员，但它指向基类成员，就好像它是派生类的成
Can someone post a simple example of starting two (Object Oriented) threads in C++. I'm looking for actual C++ thread objects that I can extend run methods on (or something similar) as opposed to calling a C-style thread library. Update - I left out any OS specific requests in the hopes that whoever replied would reply with cross platform libraries to use. I'm just making that explic
有人可以发布一个在C ++中启动两个（面向对象）线程的简单示例。 我在寻找实际的C ++线程对象，我可以扩展run方法（或类似的东西），而不是调用C风格的线程库。 更新 - 我遗漏了任何操作系统特定的请求，希望谁回复谁都会回复跨平台库使用。 我只是现在就明确表达了。 创建一个你希望线程执行的函数。 我将用一个简单的例子来演示： void task1(std::string msg) { std::cout << "task1 says: " << msg;
I'm looking for a good windows GUI library for C++. The ideal characteristics in my opinion should be: Modern. MFC, wxWidgets, Qt were started a long time ago and they don't use modern C++ features and standard library. Have a rich set of controls with decent features. The ability to drop HTML almost everywhere is a happiness for which I love wxWidgets when I don't hate it. O
我正在为C ++寻找一个好的Windows GUI库。 我认为理想的特征应该是： 现代。 MFC，wxWidgets，Qt很久以前就开始了，他们不使用现代C ++特性和标准库。 有一个丰富的控制与体面的功能。 几乎在任何地方放下HTML的能力都是我喜欢wxWidgets的快乐，当我不讨厌它时。 开源。 这是必须的。 如果购买之后有来源可用，那么它被认为是好的。 有某种形式的表单设计师。 是的，这将是伟大的。 经过多年与Delphi的合作，每次
Standard compliant C++ compilers define a __cplusplus macro which may be inspected during preprocessing to determine under what standard a file is being compiled, eg: #if __cplusplus < 201103L #error "You need a C++11 compliant compiler." #endif #include <iostream> #include <vector> int main(){ std::vector<int> v {1, 2, 3}; for (auto i : v){ std::cout <&
符合标准的C ++编译器定义了一个__cplusplus宏，在预处理过程中可以检查该宏以确定正在编译文件的标准，例如： #if __cplusplus < 201103L #error "You need a C++11 compliant compiler." #endif #include <iostream> #include <vector> int main(){ std::vector<int> v {1, 2, 3}; for (auto i : v){ std::cout << i << " "; } std::cout << std::endl;
What is the difference between static and shared libraries? I use Eclipse and there are several project types including Static Libraries and Shared Libraries? Does one have an advantage over the other? Shared libraries are .so (or in Windows .dll, or in OS X .dylib) files. All the code relating to the library is in this file, and it is referenced by programs using it at run-time. A program
静态库和共享库有什么区别？ 我使用Eclipse，并且有几个项目类型，包括静态库和共享库？ 一个人比另一个人有优势吗？ 共享库是.so（或Windows .dll或OS X .dylib）文件。 所有与库相关的代码都在这个文件中，并且在运行时被程序使用。 使用共享库的程序仅引用它在共享库中使用的代码。 静态库是.a（或Windows .lib）文件。 所有与库有关的代码都在这个文件中，并且它在编译时直接链接到程序中。 使用静态库的程序从静
I am trying to forward a std::initializer_list but no known conversion from 'std::initializer_list<A>' to 'std::initializer_list<B>' Here is the test code #include <iostream> class B { }; class A: public B { }; class not_working { private: void fun(std::initializer_list<B> p) { } public: template<typename T> not_working(std::initializer_
我想转发一个std::initializer_list但 no known conversion from 'std::initializer_list<A>' to 'std::initializer_list<B>' 这是测试代码 #include <iostream> class B { }; class A: public B { }; class not_working { private: void fun(std::initializer_list<B> p) { } public: template<typename T> not_working(std::initializer_list<T> args) {