std::is_trivial

From cppreference.com
< cpp‎ | types
 
 
Metaprogramming library
Type traits
Type categories
(C++11)
(C++14)  
(C++11)
(C++11)
(C++11)
(C++11)
(C++11)
(C++11)
(C++11)
Type properties
(C++11)
(C++11)
(C++14)
is_trivial
(C++11)
(C++11)(until C++20*)
(C++11)(deprecated in C++20)
(C++11)
Type trait constants
Metafunctions
(C++17)
Supported operations
Relationships and property queries
Type modifications
(C++11)(C++11)(C++11)
Type transformations
(C++11)(deprecated in C++23)
(C++11)(deprecated in C++23)
(C++11)
(C++11)
(C++17)

(C++11)(until C++20*)(C++17)
Compile-time rational arithmetic
Compile-time integer sequences
 
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

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>

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

See also

checks if a type is trivially copyable
(class template)
checks if a type has a default constructor
(class template)