60 lines
1.2 KiB
C++
60 lines
1.2 KiB
C++
#include <cassert>
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struct Point {
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float x, y;
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};
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struct Rect {
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Point tl, br;
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float area() const { return (br.x - tl.x) * (br.y - tl.y); }
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};
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class IShape {
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public:
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virtual float area() const { assert(false); };
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virtual ~IShape() {}
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};
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class Square : public IShape {
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public:
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Square(float extend) : m_extend(extend) {}
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float area() const override { return m_extend * m_extend; }
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private:
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float m_extend;
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};
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int main()
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{
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Rect r1{{1, 1}, {4, 4}};
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assert(r1.area() == 9.0f);
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Rect *r1_ptr = &r1;
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assert(r1_ptr->area() == 9.0f);
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// member variable pointer
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auto tl_mem_ptr = &Rect::tl; // Point Rect::*tl_mem_ptr
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assert((r1.*tl_mem_ptr).x == 1.0f);
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assert((r1_ptr->*tl_mem_ptr).x == 1.0f);
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// member function pointer
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auto area_memfn_ptr = &Rect::area; // float (Rect::*area_memfn_ptr)() const
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assert((r1.*area_memfn_ptr)() == 9.0f);
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assert((r1_ptr->*area_memfn_ptr)() == 9.0f);
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// Virtual
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Square square{2.0f};
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IShape *shape_ptr = □
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// virtual member function pointer
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auto virt_area_memfn_ptr = &IShape::area; // float (IShape::*virt_area_memfn_ptr)() const
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assert((square.*virt_area_memfn_ptr)() == 4.0f);
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assert((shape_ptr->*virt_area_memfn_ptr)() == 4.0f);
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}
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