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      std::is_trivially_copyable

      From cppreference.com
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      is_trivially_copyable
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      Defined in header <type_traits>
      template<class T >
      struct is_trivially_copyable;
      		(since C++11)

      std::is_trivially_copyable is a UnaryTypeTrait.

      If T is a trivially copyable 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_trivially_copyable or std::is_trivially_copyable_v, the behavior is undefined.

      Contents

      [edit]Template parameters

      T - a type to check

      [edit]Helper variable template

      template<class T >
      constexprbool is_trivially_copyable_v = is_trivially_copyable<T>::value;
      		(since C++17)
      [edit]

      Inherited from std::integral_constant

      Member constants

      value
      [static]
      		true if T is a trivially copyable 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_typebool
      typestd::integral_constant<bool, value>

      [edit]Notes

      Objects of trivially-copyable types that are not potentially-overlapping subobjects are the only C++ objects that may be safely copied with std::memcpy or serialized to/from binary files with std::ofstream::write() / std::ifstream::read().

      [edit]Example

      Run this code
      #include <type_traits>   struct A {int m;}; static_assert(std::is_trivially_copyable_v<A>==true);   struct B { B(B const&){}}; static_assert(std::is_trivially_copyable_v<B>==false);   struct C {virtualvoid foo();}; static_assert(std::is_trivially_copyable_v<C>==false);   struct D {int m;   D(D const&)=default;// -> trivially copyable D(int x): m(x +1){}}; static_assert(std::is_trivially_copyable_v<D>==true);   int main(){}

      [edit]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 2015C++11 T could be an array of incomplete
      class type with unknown bound       		the behavior is
      undefined in this case

      [edit]See also

      (C++11)(deprecated in C++26)
      		 checks if a type is trivial
      (class template)[edit]
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