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class template

<type_traits>

std::is_copy_assignable

template <class T> struct is_copy_assignable;

Is copy assignable


Trait class that identifies whether T is a copy assignable type.

A copy assignable type is a type that can be assigned a value or reference of the same type. This includes scalar types and copy assignable classes.

A copy assignable class is a class that has its copy assignment operator defined (either the implicitly provided one or a custom defined one).

The

is_copy_assignable class inherits from integral_constant as being either true_type or false_type, depending on whether T is copy assignable.

Template parameters

T
A complete type, or void (possible cv-qualified), or an array of unknown bound.

Member types

Inherited from integral_constant:
member typedefinition
value_typebool
typeeither true_type or false_type

Member constants

Inherited from integral_constant:
member constantdefinition
valueeither true or false

Member functions

Inherited from integral_constant:
operator bool
Returns value (public member function)

Example

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// is_copy_assignable example
#include <iostream>
#include <type_traits>

struct A { };
struct B { B& operator= (const B&) = delete; };

int main() {
  std::cout << std::boolalpha;
  std::cout << "is_copy_assignable:" << std::endl;
  std::cout << "int: " << std::is_copy_assignable<int>::value << std::endl;
  std::cout << "A: " << std::is_copy_assignable<A>::value << std::endl;
  std::cout << "B: " << std::is_copy_assignable<B>::value << std::endl;
  return 0;
}

Output:
is_copy_assignable:
int: true
A: true
B: false


See also

is_assignable
Is assignable (class template)
is_copy_constructible
Is copy constructible (class template)
is_trivially_copy_assignable
Is trivially copy assignable (class template)
is_nothrow_copy_assignable
Is copy assignable throwing no exceptions (class template)