is used SHOW( std::is_same<int, std::int64_t>::value ); // maybe false // same tests as above, except using C++17's std::is_same_v<T, U> format SHOW( std::is_same_v<int, std::int32_t> ); // maybe true SHOW( std:
is used SHOW( std::is_same<int, std::int64_t>::value ); // maybe false // same tests as above, except using C++17's std::is_same_v<T, U> format SHOW( std::is_same_v<int, std::int32_t> ); // maybe true SHOW( std::is_same_v<int, std::int64_t> ); // maybe ...
template<classT>structis_null_pointer:std::is_same<std::nullptr_t,std::remove_cv_t<T>>{}; 注解 对于std::nullptr_t,std::is_pointer是false,因为它不是内建指针类型。 在libc++ 中,std::is_null_pointer不能在 C++11 模式中使用。
template<class T> struct is_object : std::integral_constant<bool, std::is_scalar<T>::value || std::is_array<T>::value || std::is_union<T>::value || std::is_class<T>::value> {};ExampleRun this code #include <iomanip> #include <iostream> #include <type_traits> #define IS_...
char);static_assert(std::is_same_v<decltype((foo)(0)),int>);static_assert(std::is_same_v...
Same as glvalue (below). Address of an lvalue may be taken: &++i[1] and &std::endl are valid expressions. (重点来了,左值是可以取地址的,这也是区分左值和右值的唯一正确的标志) A modifiable lvalue may be used as the left-hand operand of the built-in assignment and + compound assignment...
template<classT>structis_floating_point:std::integral_constant<bool,std::is_same<float,typenamestd::remove_cv<T>::type>::value||std::is_same<double,typenamestd::remove_cv<T>::type>::value||std::is_same<longdouble,typenamestd::remove_cv<T>::type>::value>{}; ...
std::same_as<T, U> subsumes std::same_as<U, T> and vice versa. Possible implementation namespace detail { template< class T, class U > concept SameHelper = std::is_same_v<T, U>; } template< class T, class U > concept same_as = detail::SameHelper<T, U> && detail::Same...
template<class T> struct is_void : std::is_same<void, typename std::remove_cv<T>::type> {}; Example Run this code #include <type_traits> void foo(); static_assert ( std::is_void_v<void> == true and std::is_void_v<const void> == true and std::is_void_v<volatile void>...
template<class T> struct is_floating_point : std::integral_constant< bool, // 注:标准浮点数类型 std::is_same<float, typename std::remove_cv<T>::type>::value || std::is_same<double, typename std::remove_cv<T>::type>::value || std::is_same<long double, typename std::remove_...