std::is_trivial - cppreference.com (original) (raw)

| | | | | ---------------------------------------- | | ----------------------------------- | | template< class T > struct is_trivial; | | (since C++11) (deprecated in C++26) |

std::is_trivial is a UnaryTypeTrait.

If T is a trivial type, provides the member constant value equal to true. For any other type, value is false.

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

If the program adds specializations for std::is_trivial or std::is_trivial_v, the behavior is undefined.

Contents

• 1 Template parameters
• 2 Helper variable template
• 3 Inherited from std::integral_constant
  • 3.1 Member constants
  • 3.2 Member functions
  • 3.3 Member types
  • 3.4 Example
  • 3.5 Defect reports
  • 3.6 See also

[edit] Template parameters

[edit] Helper variable template

| template< class T > constexpr bool is_trivial_v = is_trivial<T>::value; | | (since C++17) (deprecated in C++26) | | ----------------------------------------------------------------------------- | | ----------------------------------- |

Inherited from std::integral_constant

Member constants

| | true if T is a trivial type, false otherwise (public static member constant) | | ------------------------------------------------------------------------------- |

Member functions

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

Member types

[edit] Example

#include   struct A { int m; }; static_assert(std::is_trivial_v == true);   struct B { B() {} }; static_assert(std::is_trivial_v == false);   // The following class shows why std::is_trivial(_v) may be a pitfall. class C { private: C() = default; };   static_assert(std::is_trivial_v == true); static_assert(std::is_trivially_default_constructible_v == false);   int main() {}

[edit] Defect reports

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

[edit] See also