1 class Base 2 { 3 public: 4 virtual void foo() = 0; 5 }; 6 7 class Derived : public Base 8 { 9 virtual void foo() override; 10 virtual void foo() const override; 11 virtual void override(); 12 }; 13 foo()14void Base::foo() 15 { 16 } 17 foo()18void Derived::foo() 19 { 20 } 21 override()22void Derived::override() 23 { 24 } 25