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// is_abstract example
#include <iostream>
#include <type_traits>
struct A { };
struct B {
virtual void fn() = 0; // pure virtual function
};
struct C : B { };
struct D : C { virtual void fn(){} };
int main() {
std::cout << std::boolalpha;
std::cout << "is_abstract:" << std::endl;
std::cout << "A: " << std::is_abstract<A>::value << std::endl;
std::cout << "B: " << std::is_abstract<B>::value << std::endl;
std::cout << "C: " << std::is_abstract<C>::value << std::endl;
std::cout << "D: " << std::is_abstract<D>::value << std::endl;
return 0;
}
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