//4_3.cpp
#include <iostream>
using namespace std;

const float PI = (float)3.14159;	//給出p的值
const float FencePrice = 35.;	//柵欄的單價
const float ConcretePrice = 20.;	//過道水泥單價

class Circle	//聲明類Circle 及其數據和方法
{
public:	//外部接口
    Circle(float r);	//構造函數
    float Circumference();	//計算圓周長
    float Area() const;	//計算圓面積
private:	//私有數據成員
    float   radius;
};

// 類的實現
Circle::Circle(float r) { radius=r; }	// 構造函數初始化數據成員radius
float Circle::Circumference()	// 計算圓的周長
{
    return 2 * PI * radius;
}
float Circle::Area() const// 計算圓的面積 
{
	//radius=12; //當定義為const時,函數內的數據成員不可以被改變
	return PI * radius * radius;
}

//主函數實現
void main ()
{
	float radius;
	float FenceCost, ConcreteCost; 
	cout << "Enter the radius of the pool: ";	 // 提示用戶輸入半徑
	cin >> radius;
	Circle Pool(radius);  	// 聲明Circle 對象
	Circle PoolRim(radius + 3);
    // 計算柵欄造價并輸出
    FenceCost = PoolRim.Circumference() * FencePrice;
    cout << "Fencing Cost is ￥" << FenceCost << endl;
    //  計算過道造價并輸出
    ConcreteCost = (PoolRim.Area() - Pool.Area())*ConcretePrice;
    cout << "Concrete Cost is ￥" << ConcreteCost << endl;
}