C++ 友元和重载问题，急!

[zcaihyl]

#include<iostream>
#include<string>
using namespace std;
class student
{
public:
string name;
int num,src;
student(string na="xx",int n=0,int s=0):name(na),num(n),src(s){}
friend istream & operator >>(istream &,student &);
friend ostream & operator <<(ostream &,student &);
};
istream& operator >>(istream& a1,student& a2)
{
cout<<"请输入姓名"<<endl;
a1>>a2.name;
cout<<"请输入学好"<<endl;
a1>>a2.num;
cout<<"请输入分数"<<endl;
a1>>a2.src;
cout<<endl;
return a1;
}
ostream & operator <<(ostream &a1,student &a2)
{
a1<<"结果如下"<<endl<<a2.name<<endl<<a2.num<<endl<<a2.src<<endl;
return a1;
}
int main()
{
student x,y;
cin>>x;
cout<<x;
cin>>y;
cout<<y;
return 0;
}

请问为什么有四个错误说>> 和<< 混乱；还有请问友元函数能访问类的私有成员吗？

[arong1234]

友元当然可以访问私有成员
至于你说的“混乱”，我估计是ambiguous？这表示模糊不清，不是混乱的意思。下次记得直接贴错误信息原文，贴自己“理解后”的文字，很可能延缓你获得答案的过程

至于ambiguous的原因：这是vc6的一个知名bug，如果友元和 std同用就会出现错误，因此立刻升级编译器（微软2005年还是2006就不再支持vs6了）

[xiaoshi935]

如果你用vc6.0的话就是有问题的，必须实现声明，我写了一段代码，你看看先，如果还有不对的话，可以再探讨。

#include <iostream> 
#include <string> 
using namespace std; 

class student;
istream & operator >>(istream &,student &);
ostream & operator <<(ostream &,student &); 
class student {
private:
	string name; 
	int num,src; 
public:
	student(string na="xx",int n=0,int s=0):name(na),num(n),src(s){} 
	friend istream & operator >>(istream &,student &); 
	friend ostream & operator <<(ostream &,student &); 
}; 

istream& operator >>(istream& a1,student& a2) {
	cout <<"请输入姓名：" <<endl; 
	a1>>a2.name; 
	cout <<"请输入学号：" <<endl; 
	a1>>a2.num; 
	cout <<"请输入分数：" <<endl; 
	a1>>a2.src; 
	cout <<endl; 
	return a1; 
} 

ostream & operator <<(ostream &a1,student &a2) {
	a1 <<"结果如下：" <<endl <<a2.name <<endl <<a2.num <<endl <<a2.src <<endl; 
	return a1; 
} 

int main() {
	student x,y; 
	cin>>x; 
	cout <<x; 
	cin>>y; 
	cout <<y; 
	return 0; 
} 

[AbnormalSubmarine]

代码是好的！
可能是你的环境的问题
我在vc2005 跑你的代码一切正常

[AbnormalSubmarine]

[Quote=引用楼主 zcaihyl 的帖子:]
#include <iostream>
#include <string>
using namespace std;
class student
{
public:
string name;
int num,src;
student(string na="xx",int n=0,int s=0):name(na),num(n),src(s){}
friend istream & operator >>(istream &,student &);
friend ostream & operator < <(ostream &,student &);
};
istream& operator >>(istream& a1,student& a2)
{
cout < <"请输入姓名" < <endl;
a1>>a2.nam…
[/Quote]

friend istream & operator >>(istream &,student &);
friend ostream & operator < <(ostream &,student &); //这个符号中间不是多了空格吗？

[Sou2012]

测试通过

#ifndef _TTT_H_
#define _TTT_H_

#include <iostream> 
#include <string>

class student
{
public:
	std::string name;
	int num, score;
	student(std::string na = "xx", int n = 0, int s = 0) : name(na), num(n), score(s) {} 
	friend std::istream &operator>>(std::istream &, student &); 
	friend std::ostream &operator<<(std::ostream &, student &); 
}; 

#endif

#include <iostream> 
#include <string>
#include "TTT.h"
using namespace std;

istream &operator>>(istream &a1,student &a2) 
{ 
	cout << "please enter name:" << endl; 
	a1 >> a2.name; 
	cout << "please enter your school number:" << endl; 
	a1 >> a2.num; 
	cout << "please enter your score:" << endl; 
	a1 >> a2.score; 
	cout << endl; 
	return a1; 
} 

ostream &operator<<(ostream &a1,student &a2) 
{ 
	a1 << "result as below:" << endl << a2.name << endl << a2.num << endl << a2.score << endl; 
	return a1; 
} 

int main() 
{ 
	student x, y; 
	cin >> x; 
	cout << x;
	cin >> y; 
	cout << y; 
	return 0; 
}

[Sou2012]

以上结果是VC6下编译运行的

[zhangzhongke007]

貌似3楼的说的很对！

[ytzxj]

ostream & operator < <(ostream &a1,student &a2)
{
a1 < <"结果如下" < <endl < <a2.name < <endl < <a2.num < <endl < <a2.src < <endl;
return a1;
}
错了 l写成1了！！

[zcaihyl]

谢谢啊，但是，我试过了，好像友元不能访问私有成员，不知道是不是编译器的问题。

[driverSir]

言法错误，一点调度