std::is_trivial

 

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

If T is Template:concept (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 > 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

Run this code

#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

is_trivially_copyable (C++11)	checks if a type is trivially copyable (class template)
std::experimental::is_trivial_v (library fundamentals TS)	variable template alias of std::is_trivial::value (variable template)