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std::is_class

STD：：是[医]类

Defined in header ​​
template< class T > struct is_class;​(since C++11)

检查是否T是类类型。提供成员常量。value等于true，如果T是类类型%28，而不是联合%29。否则，value等于false...

值声明的类型。struct关键字是类，所以这个特征是true用于“结构”。

模板参数

T-a type to check

辅助变量模板

template< class T > inline constexpr bool is_class_v = is_class::value;​(since C++17)

继承自STD：积分[医]常量

成员常数

value statictrue if T is a class or struct , false otherwise (public static member constant)

成员函数

operator boolconverts the object to bool, returns value (public member function)
operator() (C++14)returns value (public member function)

成员类型

TypeDefinition
value_typebool
typestd::integral_constant<bool, value>

可能的实施

命名空间细节{模板<class T>焦炭测试%28 int T：：%2A%29；struct 2{char c二模板<class T>两个测试%28%29}模板<class T>结构是[医]类别：STD：：整数[医]常数<bool，尺寸%28详细：：测试<T>%280%29%29=1&&%21 std：：is[医]联合<T>*价值>{}；

*。

例

二次

#include <iostream>
#include <type_traits>
 
struct A {};
 
class B {};
 
enum class C {};
 
int main() 
{
    std::cout << std::boolalpha;
    std::cout << std::is_class<A>::value << '\n';
    std::cout << std::is_class<B>::value << '\n';
    std::cout << std::is_class<C>::value << '\n';
    std::cout << std::is_class<int>::value << '\n';
}

二次

产出：

二次

true
true
false
false

二次

另见

is_union (C++11)checks if a type is an union type (class template)

 © cppreference.com

在CreativeCommonsAttribution下授权-ShareAlike未移植许可v3.0。

http：//en.cppreference.com/w/cpp/type/is[医]类

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