C++封闭类的复制构造函数

原题：mooc北大的c++国家精品课http://cxsjsxmooc.openjudge.cn/2019t3summerall/011/

#include 
#include 
using namespace std;
class Base {
public:
	int k;
	Base(int n):k(n) { };
};
class Big
{
public:
	int v;
	Base b;
	Big(int init_n):b(init_n),v(init_n){         //构造函数
	}
	Big(const Big& init_c)             //这里这样定义复制构造函数是不对的
	{
		v=init_c.v;
		b=init_c.b;
	}
	
	
};
int main()
{
	int n;
	while(cin >>n) {
		Big a1(n);
		Big a2 = a1;
		cout << a1.v << "," << a1.b.k << endl;
		cout << a2.v << "," << a2.b.k << endl;
	}
}

错误如上，

正确代码如下：

#include 
#include 
using namespace std;
class Base {
public:
	int k;
	Base(int n):k(n) { };
};
class Big
{
public:
	int v;
	Base b;
	Big(int init_n):b(init_n),v(init_n){
	}
	Big(const Big& init_c):v(init_c.v),b(init_c.b)         //这样构造复制构造函数是正确的 
	{
	}
	
	
};
int main()
{
	int n;
	while(cin >>n) {
		Big a1(n);
		Big a2 = a1;
		cout << a1.v << "," << a1.b.k << endl;
		cout << a2.v << "," << a2.b.k << endl;
	}
}