/* 程序11.3：基類和包含類初始化.cpp：*/
#include<iostream>		//包含頭文件
#include<cmath>			//包含頭文件
#include<string>		//包含頭文件
using namespace std;	//使用名字空間std

class Point				//聲明基類Point
{
private:
	float fX,fY;
public:
	Point(float X=0,float Y=0)	//聲明基類構造符函數
	{
	fX=X;	fY=Y;
	}
	float GetX()	//通過公共成員函數訪問私有成員變量
	{
		return fX;
	}
	float GetY()
	{
		return fY;
	}
};
class Line			//聲明子類Line
{
public:
	Point P1,P2;	//包含兩個點對象
	Line(float X1=0,float Y1=0,
		 float X2=0,float Y2=0):P1(X1,Y1),P2(X2,Y2)
	{
			//不做任何事情;
	}
float Length(Point P1,Point P2)
	{
	float L1;
	float XZ=P1.GetX()-P2.GetX();
	float YZ=P1.GetY()-P2.GetY();
	L1=sqrt(pow(XZ,2)+pow(YZ,2));
	return L1;
	}
void Display(string S1,string S2)
	{
	cout<<S1<<"和"<<S2<<"兩點之間的距離是："<<Length(P1,P2)<<endl;
	}
};
class Triangle:public Line	//聲明子類Triangle
{
private:
	Point P3;
public:
	Triangle(float X1=0,float Y1=0,float X2=0,float Y2=0,
		     float X3=0,float Y3=0):Line(X1,Y1,X2,Y2),P3(X3,Y3)
	{
			//不做任何事情;
	}
	float TriLength()
	{
	float TriL1;
	TriL1=Length(P1,P2)
		 +Length(P2,P3)
		 +Length(P3,P1);
	cout<<"總距離是："<<TriL1<<endl;
	return TriL1;
	}
};

int main()
{
	Triangle obj(0,0,10,0,0,10);		//聲明子類對象
	obj.TriLength();
	return 0;
}