W3cubDocs

/C++

std::is_trivial

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

If T is TrivialType (that is, a scalar type, a trivially copyable class with a trivial default constructor, or array of such type/class, possibly cv-qualified), provides the member constant value equal true. For any other type, value is false.

The behavior is undefined if std::remove_all_extents_t<T> is an incomplete type and not (possibly cv-qualified) void.

Template parameters

T - a type to check

Helper variable template

template< class T >
inline constexpr bool is_trivial_v = is_trivial<T>::value;
(since C++17)

Inherited from std::integral_constant

Member constants

value
[static]
true if T is a trivial type , false otherwise
(public static member constant)

Member functions

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

Member types

Type Definition
value_type bool
type std::integral_constant<bool, value>

Possible implementation

template< class T >
struct is_trivial : std::integral_constant< 
    bool,
    std::is_trivially_copyable<T>::value &&
    std::is_trivially_default_constructible<T>::value 
> {};

Example

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

Output:

true
false

See also

(C++11)
checks if a type is trivially copyable
(class template)

© cppreference.com
Licensed under the Creative Commons Attribution-ShareAlike Unported License v3.0.
http://en.cppreference.com/w/cpp/types/is_trivial