Webstd::type_info 定义于头文件 class type_info; 类 type_info 保有一个类型的实现指定信息,包括类型的名称和比较二个类型相等的方法或相对顺序。 这是 typeid 运算符所返回的类。 type_info 既非 可复制构造 (CopyConstructible) 亦非 可复制赋值 (CopyAssignable) 。 成员函数 (C++11) WebMay 17, 2011 · struct any { std::type_info const& _info; void* _address; }; And a templated constructor: template any::any (T* t): _info (typeid (*t)), _address (dynamic_cast (t)) { } This is, basically, boost::any. Now we need to "augment" it with our comparison mechanism.
typeid operator - cppreference.com
WebJan 29, 2014 · 1 Answer Sorted by: 3 You can't use run-time type information as a compile-time template parameter. In C++11, decltype can give you the static type of an expression: Do (); Historically, the best you could do would be to use another function template to infer the type from its argument: WebFeb 13, 2024 · To summarize, for static types, compiler has global variables ( std::type_info) initialized. At places where the code calls typeid, the machine code just gets the corresponding std::type_info global objects that are already initialized. Done. Dynamic Type Here we have an example with dynamic types. Let's check the assembly. pnc online small business
std::type_info: std::type_info - Linux Man Pages (3) - SysTutorials
WebOct 21, 2024 · C++ allows us to inspect the dynamic type of an object with the typeid () operator which gives us a std::type_info object. Either the compiler knows the type of the object at compile time, or the compiler has stored the necessary type information inside the object and can retrieve it at runtime. Share Improve this answer Follow Web解释 1) 指代一个表示 类型 类型的 std::type_info 对象。 若 类型 为引用类型,则结果所指代的 std::type_info 对象表示被引用的类型。 2) 检验表达式 表达式 a) 若 表达式 为标识某个 多态类型 (即声明或继承至少一个 虚函数 的类)对象的 泛左值表达式 ,则 typeid 表达式对该表达式求值,然后指代表示该表达式动态类型的 std::type_info 对象。 若该泛左值表达式 … WebOct 14, 2024 · Solution 1. std::type_info::name always returns two different strings for two different types, otherwise it means that the compiler lost itself while resolving types and you shouldn't use it anymore. Reference tells : "before returns true if the type precedes the type of rhs in the collation order. The collation order is just an internal order ... pnc online support