WebFeb 5, 2024 · But this approach breaks down for other features of std::any. For example, to copy an std::any: any a (42); any b = a; We need to call the constructor of the type of the object passed to any. And a type_info, which is runtime type information, is not enough to do that. We need code with the static type to call the copy constructor. WebAug 28, 2024 · std::any 是 c++17 标准新提供的类，作用是存储任意类型的一段内存，并可以重复赋值，在赋值后可以使用 std::any_cast 将 std::any 所存储的值转换成特定类型，如果 std::any 中存储的值的类型与目标类型不匹配，则会抛出 std::bad_any_cast 异常。. 获取指针时， any_cast 的入 ...
std::any - cppreference.com
Web您应该注意的其他问题包括实现移动忘记noexcept的问题、在能够使用的时候不使用零规则、丢失良好的默认移动操作而不用 =default 取回它们、在不应该使用时使用 std::move（从您仍在使用的对象中窃取）、在相关时不使用 std::forward。. 定位 new. 定位 new 的概念是，我们可以在特定的给定内存位置创建 ... WebOct 28, 2024 · 1) Constructs an empty object. 2-3) Copies (2) or moves (3) content of other into a new instance, so that any content is equivalent in both type and value to those of other prior to the constructor call, or empty if other is empty. Formally, 2) If other is empty, the constructed object is empty. fun activities in march to do at home
是否提倡使用std::any？ - 知乎
WebA trait to emulate dynamic typing. Most types implement Any.However, any type which contains a non-'static reference does not.See the module-level documentation for more details. WebFeb 5, 2024 · 1) An object of class any stores an instance of any type that satisfies the constructor requirements or is empty, and this is referred to as the state of the class any object. The stored instance is called the contained object. Two states are equivalent if they are either both empty or if both are not empty and if the contained objects are equivalent. WebMay 28, 2024 · 使用c++实现boost::any类 any类可以存放任意类型数据，如: void test_any() { any any_a1(123); int a2 = any_cast(any_a1); int* p_a2 = any_cast(&any_a1); std::cout << … girder and header span charts