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CPP: make_shared and shared_ptr demo
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| #include <iostream> | |
| #include <iomanip> | |
| #include <vector> | |
| #include <sstream> | |
| #include <memory> | |
| #include <cmath> | |
| using namespace std; | |
| const double PI = 3.14; | |
| class Figure { | |
| public: | |
| virtual string Name() const = 0; | |
| virtual double Perimeter() const = 0; | |
| virtual double Area() const = 0; | |
| }; | |
| class Triangle : public Figure { | |
| public: | |
| Triangle(double a, double b, double c) : A(a), B(b), C(c) {} | |
| virtual string Name() const override { return "TRIANGLE"; } | |
| virtual double Perimeter() const override { return A + B + C; } | |
| virtual double Area() const override { | |
| double p = Perimeter() / 2; | |
| return sqrt(p * (p - A) * (p - B) * (p - C)); | |
| } | |
| private: | |
| double A; | |
| double B; | |
| double C; | |
| }; | |
| class Rect : public Figure { | |
| public: | |
| Rect(double w, double h) : W(w), H(h) {} | |
| virtual string Name() const override { return "RECT"; } | |
| virtual double Perimeter() const override { return (W + H) * 2; } | |
| virtual double Area() const override { return W * H; } | |
| private: | |
| double W; | |
| double H; | |
| }; | |
| class Circle : public Figure { | |
| public: | |
| Circle(double r) : R(r) {} | |
| virtual string Name() const override { return "CIRCLE"; } | |
| virtual double Perimeter() const override { return 2*PI*R; } | |
| virtual double Area() const override { return PI*R*R; } | |
| private: | |
| double R; | |
| }; | |
| shared_ptr<Figure> CreateFigure(istringstream& is) { | |
| string fig_name; | |
| is >> fig_name; | |
| if (fig_name == "RECT") { | |
| double w, h; | |
| is >> w >> h; | |
| return make_shared<Rect>(w, h); | |
| } else if (fig_name == "CIRCLE") { | |
| double r; | |
| is >> r; | |
| return make_shared<Circle>(r); | |
| } else if (fig_name == "TRIANGLE") { | |
| double a, b, c; | |
| is >> a >> b >> c; | |
| return make_shared<Triangle>(a, b, c); | |
| } else { | |
| throw logic_error("Incorrect figure type"); | |
| } | |
| } | |
| int main() { | |
| vector<shared_ptr<Figure>> figures; | |
| for (string line; getline(cin, line); ) { | |
| istringstream is(line); | |
| string command; | |
| is >> command; | |
| if (command == "ADD") { | |
| figures.push_back(CreateFigure(is)); | |
| } else if (command == "PRINT") { | |
| for (const auto& current_figure : figures) { | |
| cout << fixed << setprecision(3) | |
| << current_figure->Name() << " " | |
| << current_figure->Perimeter() << " " | |
| << current_figure->Area() << endl; | |
| } | |
| } | |
| } | |
| return 0; | |
| } |
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