使用抽象类C++进行单独编译

// 抽象类 Shape
class Shape {
public:
    virtual double area() const = 0; // 纯虚函数
    virtual void draw() const = 0;   // 纯虚函数
    virtual ~Shape() {}              // 虚析构函数
};

// 派生类 Circle
class Circle : public Shape {
private:
    double radius;
public:
    Circle(double r) : radius(r) {}
    double area() const override {
        return 3.14159 * radius * radius;
    }
    void draw() const override {
        std::cout << "Drawing a circle." << std::endl;
    }
};

// 派生类 Square
class Square : public Shape {
private:
    double side;
public:
    Square(double s) : side(s) {}
    double area() const override {
        return side * side;
    }
    void draw() const override {
        std::cout << "Drawing a square." << std::endl;
    }
};

int main() {
    Shape* shapes[2];
    shapes[0] = new Circle(5);
    shapes[1] = new Square(4);

    for (int i = 0; i < 2; ++i) {
        shapes[i]->draw();
        std::cout << "Area: " << shapes[i]->area() << std::endl;
        delete shapes[i];
    }

    return 0;
}

shape.h
circle.h
square.h
shape.cpp
circle.cpp
square.cpp
main.cpp

g++ -c shape.cpp -o shape.o
g++ -c circle.cpp -o circle.o
g++ -c square.cpp -o square.o
g++ -c main.cpp -o main.o
g++ shape.o circle.o square.o main.o -o my_program