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

class person{
private:
string name,address;
char sex;
int ID;
public:
person(){name="king";address="09109";sex='M';ID=109;}
person(string name1,string address1,char sex1,int ID1);
void New_set();
void out_message();
friend ostream& operator<<(ostream& stream,person& p);
friend istream& operator>>(istream& stream,person& p);
};

void person::out_message()
{
cout<<"姓 名:"<<name<<endl;
cout<<"性 别:"<<sex<<endl;
cout<<"地 址:"<<address<<endl;
cout<<"身份证号:"<<ID<<endl;
}

person::person(string name1,string address1,char sex1,int ID1)
{
name=name1;
address=address1;
sex=sex1;
ID=ID1;
}

void person::New_set()
{

cout<<"请输入姓名:";
cin>>name;
cout<<"请输入地址:";
cin>>address;
cout<<"请输入性别:";
cin>>sex;
cout<<"请输入身份证号:";
cin>>ID;
}

ostream& operator<<(ostream& stream,person& p)
{
p.out_message();
return stream;
}

istream& operator>>(istream& stream,person& p)
{
p.New_set();
return stream;
}

void main()
{
person A;
cout<<A<<endl;
cout<<"请输入更新后的信息:"<<endl;
cin>>A;
cout<<A<<endl;
}


运行结果：
--------------------Configuration: Cpp2 - Win32 Debug--------------------
Compiling...
Cpp2.cpp
E:\C++\I-O流实验\Cpp2.cpp(63) : error C2593: 'operator <<' is ambiguous
E:\C++\I-O流实验\Cpp2.cpp(65) : error C2593: 'operator >>' is ambiguous
E:\C++\I-O流实验\Cpp2.cpp(66) : error C2593: 'operator <<' is ambiguous
Error executing cl.exe.

Cpp2.exe - 3 error(s), 0 warning(s)

哪个大虾帮忙看下撒
以前都没问题的啊~~~

#include<iostream.h>

class person{
private:
char name,address;
char sex;
int ID;
public:
person(){name='k';address='0';sex='M';ID=109;};
person(char name1,char address1,char sex1,int ID1);
void New_set(istream& stream);
void out_message(ostream& stream);
friend ostream& operator<<(ostream& stream,person& p);
friend istream& operator>>(istream& stream,person& p);
};

void person::out_message(ostream& stream)
{
stream<<"姓 名:"<<name<<endl;
stream<<"性 别:"<<sex<<endl;
stream<<"地 址:"<<address<<endl;
stream<<"身份证号:"<<ID<<endl;
}

person::person(char name1,char address1,char sex1,int ID1)
{
name=name1;
address=address1;
sex=sex1;
ID=ID1;
}

void person::New_set(istream& stream)
{
cout<<"请输入姓名:";
stream>>name;
cout<<"请输入地址:";
stream>>address;
cout<<"请输入性别:";
stream>>sex;
cout<<"请输入身份证号:";
stream>>ID;
}

ostream& operator<<(ostream& stream,person& p)
{
p.out_message(stream);
return stream;
}

istream& operator>>(istream& stream,person& p)
{
p.New_set(stream);
return stream;
}

void main()
{
try{
person A;
cout<<A;
cout<<"请输入更新后的信息:"<<endl;
cin>>A;
cout<<A<<endl;
}
catch(...)
{
cout<<"error";
}
}
大概是因为string不能重载吧.
用VS.2003可以编译.建议你用新的编译器.

友元重载函数声明和重载函数实现有二义性，可以通过下面两个方法解决：
1.在友元声明处实现函数，这样不会有二义性：

[CODE] friend ostream& operator<<(ostream& stream,person& p)
{
p.out_message();
return stream;
}
friend istream& operator>>(istream& stream,person& p)
{
p.New_set();
return stream;
}[/CODE]
2.在友元声明前声明一下重载函数的原型，避免造成二义性

[CODE]class person;
ostream& operator<<(ostream& stream,person& p);
istream& operator>>(istream& stream,person& p);

class person{
private:
string name,address;
char sex;
int ID;
public:
person(){name="king";address="09109";sex='M';ID=109;}
person(string name1,string address1,char sex1,int ID1);
void New_set();
void out_message();
friend ostream& operator<<(ostream& stream,person& p);
friend istream& operator>>(istream& stream,person& p);
};[/CODE]