#include<iostream>

using namespace std;

class CSale

{

public :

CSale();

CSale(char *cName,int iPrice)

{

strncpy(m_cName,cName,128);

m_iPrice=iPrice;

}

friend ostream& operator<<(ostream& os,const CSale s)

{

cout << "Name: " << s.m_cName << ' ' ;

cout << "Price: " << s.m_iPrice<< ' ';

return os;

}

protected:

char m_cName[128];

int m_iPrice;

};

int main()

{

CSale sale("apple",900);

cout << sale << endl;

return 0;

}

代码中的friend ostream& operator<<(ostream& os,const CSale s)和return os;是什么意思

还有什么是流对象？