std::is_trivial

< cpp‎ | types

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

std::is_trivial is an UnaryTypeTrait.

If T is a trivial type, the base characteristic is std::true_type. For any other type, the base characteristic is std::false_type.

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

The behavior of a program that adds specializations for std::is_trivial or std::is_trivial_v (since C++17) is undefined.

Template parameters

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>

Example

#include <type_traits>
 
struct A { int m; };
static_assert(std::is_trivial_v<A> == true);
 
struct B { B() {} };
static_assert(std::is_trivial_v<B> == false);
 
int main() {}

Defect reports

The following behavior-changing defect reports were applied retroactively to previously published C++ standards.

DR	Applied to	Behavior as published	Correct behavior
LWG 2015	C++11	`T` could be an array of incomplete class type with unknown bound	the behavior is undefined in this case

is_trivially_copyable (C++11)	checks if a type is trivially copyable (class template)
is_default_constructibleis_trivially_default_constructibleis_nothrow_default_constructible (C++11)(C++11)(C++11)	checks if a type has a default constructor (class template)