#include<iostream>//21
using namespace std;
//友元函式
class A
{
public:
	friend void modifyA(A *pA, int _a);
	A(int _a, int _b)
	{
		this->a = a;
		this->b = b;
	}
	int getA()
	{
		return this->a;
	}
private:
	int a;
	int b;
};
void modifyA(A *pA, int _a)//全域性函式宣告成類的友元函式，修改了類的私有屬性，本來全域性函式是不能夠修改類的私有屬性的
{
	pA->a = _a;
}
int main()
{
	A a1(1, 2);
	cout << a1.getA() << endl;
	modifyA(&a1, 3);
	cout << a1.getA() << endl;
	system("pause");
	return 0;
}