该问题来自社区帖: https://bbs.csdn.net/topics/617130493.
ostream & operator<<(ostream &cout, person &p)//本质 operator<<(cout,p) 简化 cout<<p
{
cout << "m_A=" << p.m_A << " m_B=" << p.m_B;
return cout;
}
返回cout为什么前面要用ostream & operator,而且&和operator之间还有空格