C++接口

#include <iostream>
using namespace std;
// 如果类中至少有一个纯虚函数，则这个类就是抽象类
// 基类
class Shape
{
public:
	// 纯虚函数
	virtual int getArea() = 0;
	void setWidth(int w)
	{
		width = w;
	}

	void setHeight(int h)
	{
		height = h;
	}
protected:
	int width;
	int height;
};

// 派生类
class Rectangle :public Shape
{
public:
	int  getArea()
	{
		return (width*height);
	}
};

class Triangle :public Shape
{
public:
	int getArea()
	{
		return (width*height) / 2;
	}
};

int main(void)
{
	Rectangle Rect;
	Triangle Tri;
	Rect.setWidth(6);
	Rect.setHeight(7);
	cout << Rect.getArea() << endl;

	Tri.setWidth(6);
	Tri.setHeight(7);
	cout << Tri.getArea() << endl;
	system("pause");
	return 0;
}