#include<iostream>
#include<string>
using namespace std;
class king{
public:
	king(int data) :num(data)//初始化參數(shù)列表初始化數(shù)據(jù)
	{
		cout << num << endl;
	}
	void print()const//常成員函數(shù)
	{
		cout << "hello!" << endl;
	}
	void printdata()//普通函數(shù)
	{
		str = "lijue";
		cout << str << endl;
	}
protected:
	string str;
	const int num;//常數(shù)據(jù)成員
};
int main(){
	king prince(18);
	prince.print();//普通對象調(diào)用常成員函數(shù)
	const king boy(12);
	boy.print();//常對象調(diào)用常成員函數(shù)
	while (1);
	return 0;
}

//普通友元函數(shù)，可以打破權(quán)限的限制
#include<iostream>
using namespace std;
void print();
class myfriend{
public:
protected:
	int data = 150;
	friend void print(myfriend&k){
		cout << k.data << endl;
	}
};
int main(){
	myfriend k;
	print(k);
	while (1);
	return 0;
}

//以另一個類的成員函數(shù)充當友元函數(shù)
#include<iostream>
using namespace std;
class myfriend;
class I{
public:
	void print();
protected:
};
class myfriend{
public:
	friend void I::print();
protected:
	int data = 150;		
};
void I::print()
{
	myfriend k;
	cout << k.data << endl;
}
int main(){
	I K;
    K.print();
	while (1);
	return 0;
}

//友元類
#include<iostream>
using namespace std;
class A;
class B{
public:
	friend class A;
protected:
	int data = 123;
};
class A{
public:
	void printData()
   {
		B l;
		cout << l.data << endl;
   }
protected:
       };
int main()
{
	A l;
	l.printData();
	while (1);
	return 0;
}