#include <iostream>
using namespace std;
/* run this program using the console pauser or add your own getch, system("pause") or input loop */
//class
class Circle
{
private:
	double area;	
public:
	double radius;
	//double area;
	double showArea()
	{
		area = 3.14159*radius*radius;
		return area;
	}
	string compare(Circle * a1)
	{
		if(radius > a1->radius)return "大於";
		else if(radius < a1->radius)return "小於";
		else return "等於";	
	}
	void copy(Circle * a1)
	{
		a1->radius = radius;	
	}	
};
int main(int argc, char** argv) {
	//1.物件函數，傳遞參數 = 若是一個很大的物件變數（影音編輯軟體裡面，傳遞一個AVI影片檔案）
	//缺點：會在記憶體，不斷配置很大的空間，造成記憶體擁塞
	//改良方法：傳遞的參數 = 物件指標（就不會再配置新的記憶體空間）
	
	//2.物件指標
	//（1）宣告
	//Circle * a1;
	//Circle * a1 = new Circle;

	//（2）建立物件（配置記憶體空間），有沒有()都可以 
	//a1 = new ClassName
	//a1 = new ClassName()
	
	//3.宣告，配置記憶體 
	//4.指派 1 (a4 = new Circle） 
	Circle * a1;
	a1 = new Circle;
	
	Circle * a2 = new Circle;
	Circle * a3 = new Circle();
	
	cout<<" a1 = "<<a1<<endl;
	cout<<" a2 = "<<a2<<endl;
	cout<<" a3 = "<<a3<<endl;
	
	//4.指派 2 (a4 = 其它指標） 
	Circle * a4 = new Circle;
	//指標的空間，若沒有刪除，程式結束後，還會佔據記憶體空間
	//所以，若沒有用到的，就要先釋放記憶體：delete a4
	delete a4;
	//因為a4要指派到另外一個空間，所以原本的舊空間，要先釋放 ：delete a4;
	a4 = a1; 
	cout<<" a4 = "<<a4<<endl;
	
	//4.指派 3(a6 = &其它物件變數）
	Circle a5;
	Circle * a6 = new Circle;
	a6 = &a5;
	cout<<"\n a6 = "<<a6<<endl;
	
	//5.成員存取
	Circle * a7 = new Circle;
	a7->radius = 3;
	cout<<"\n a7.area = "<<a7->showArea()<<endl;
	
	//6.成員存取的矛盾：資料數值不合理
	Circle * a8 = new Circle;
	a8->radius = 5;
	//a8->area = 5;
	
	//什麼的數據，不合理 ：因為半徑，面積數值，矛盾 
	//改善方法：封裝（把成員變成private: 
	//這個時候，要取得a->area，只能夠用函式來設定了
	cout<<"\n a8.area = "<<a8->showArea()<<endl;
	
	//7.物件指標參數（函式的參數，用物件指標）：compare(Circle * p1) 
	Circle * a9 = new Circle;
	a9->radius = 7;
	cout<<"\na9 半徑"<<a9->compare(a8)<<" a8 "<<endl; 
	
	Circle a10;
	a10.radius = 9;
	cout<<"\na9 半徑"<<a9->compare(&a10)<<" a10 "<<endl; 
	
	//8.物件指標參數（函式的參數，用物件指標）：
	Circle a11;
	a11.radius = 10;
	Circle a12;
	a11.copy(&a12);
	cout<<"\n a12.radius = "<<a12.radius<<endl;
	
	//9.釋放所配置的記憶體
	delete a1,a2,a3,a6,a7,a8; 
	//有配置記憶體的（new），最後都要delete 
	
	
	
	return 0;
}