具体过程是这样的~
derived d(6,7,8);
base c=d;
这里的d 先转换成 base类，然后调用base的拷贝构造函数，因为你的base 没有定义Copy构造函数，就调用默认的，字节Copy。
这样定义你就能看明白真正的工作原理了。
class CA
{
public:
CA(int a, int b, int c) {m_a = a; m_b = b; m_c = c; std::cout << "Constructor CA\n";};
CA(const CA &a) { m_a = a.m_a; m_b = a.m_b; m_c = a.m_c; std::cout << "Copy Construcotr:CA\n";}
public:
int m_a;
int m_b;
int m_c;
};
class CB: public CA
{
public:
CB():CA(0, 1, 2){ std::cout << "Constructor CB\n";};
};
