std::is_polymorphic

template< class T >
struct is_polymorphic;

If T is a polymorphic class (that is, a non-union class that declares or inherits at least one virtual function), provides the member constant value equal true. For any other type, value is false.

If T is a non-union class type, T shall be a complete type; otherwise, the behavior is undefined.

Template parameters

Helper variable template

template< class T >
inline constexpr bool is_polymorphic_v = is_polymorphic<T>::value;

Example

#include <iostream>
#include <type_traits>
 
struct A {
    int m;
};
 
struct B {
    virtual void foo();
};
 
struct C : B {};
 
int main()
{
    std::cout << std::boolalpha;
    std::cout << std::is_polymorphic<A>::value << '\n';
    std::cout << std::is_polymorphic<B>::value << '\n';
    std::cout << std::is_polymorphic<C>::value << '\n';
}

false
true
true

See also