std::is_compound(3) | C++ Standard Libary | std::is_compound(3) |
NAME¶
std::is_compound - std::is_compound
Synopsis¶
Defined in header <type_traits>
template< class T > (since C++11)
struct is_compound;
If T is a compound type (that is, array, function, object pointer, function
pointer,
member object pointer, member function pointer, reference, class, union, or
enumeration, including any cv-qualified variants), provides the member
constant
value equal true. For any other type, value is false.
The behavior of a program that adds specializations for is_compound
or is_compound_v
(since C++17) is undefined.
Template parameters¶
T - a type to check
Helper variable template
template< class T > (since C++17)
inline constexpr bool is_compound_v = is_compound<T>::value;
Inherited from std::integral_constant
Member constants¶
value true if T is a compound type , false otherwise
[static] (public static member constant)
Member functions¶
operator bool converts the object to bool, returns value
(public member function)
operator() returns value
(C++14) (public member function)
Member types¶
Type Definition
value_type bool
type std::integral_constant<bool, value>
Notes¶
Compound types are the types that are constructed from
fundamental types. Any C++
type is either fundamental or compound.
Possible implementation¶
template< class T >
struct is_compound : std::integral_constant<bool,
!std::is_fundamental<T>::value> {};
Example¶
// Run this code
#include <iostream>
#include <type_traits>
int main() {
class cls {};
std::cout << (std::is_compound<cls>::value
? "`cls` is compound"
: "`cls` is not a compound") << '\n';
std::cout << (std::is_compound_v<int>
? "`int` is compound"
: "`int` is not a compound") << '\n';
}
Output:¶
`cls` is compound
`int` is not a compound
See also¶
is_fundamental checks if a type is a fundamental type
(C++11) (class template)
is_scalar checks if a type is a scalar type
(C++11) (class template)
is_object checks if a type is an object type
(C++11) (class template)
is_array checks if a type is an array type
(C++11) (class template)
2022.07.31 | http://cppreference.com |