C++

Reference

<type_traits>

class template
<type_traits>

std::is_base_of

template <class Base, class Derived> struct is_base_of;
Is base class of

Trait class that identifies whether Base is a base class of (or the same class as) Derived, without regard to their const and/or volatile qualification. Only classes that are not unions are considered.

The class inherits from integral_constant as being either true_type or false_type, depending on whether Derived inherits from Base.


Template parameters

Base
A type.
Derived
A type.
This shall be a complete type if both Base and Derived are different class types.
This shall be a complete type if both Base and Derived are different non-union class types.

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_base_of example
#include <iostream>
#include <type_traits>

struct A {};
struct B : A {};

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

Output:
is_base_of:
int, int: false
A, A: true
A, B: true
A, const B: true
A&, B&: false
B, A: false


See also

is_class
Is non-union class (class template)
is_same
Is same type (class template)
is_convertible
Is convertible (class template)