std::is_trivial (3) - Linux Man Pages

std::is_trivial: std::is_trivial

NAME

std::is_trivial - std::is_trivial

Synopsis


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


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


Inherited from std::integral_constant

Member constants


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

Member functions


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


operator() returns value
              (public member function)
(C++14)

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