初学者问题，望高手指教！

清风

#include "stdafx.h"
#include "iostream.h"

class student  
{
    friend ostream & operator<<(ostream &,const student & );
    friend istream & operator>>(istream & ,student & );
public:
    student(student &);
    student(int,string,string);
    int getAge();
    string getName();
    string getClassName();
    void setAge(int);
    void setName(string);
    void setClassName(string);
    virtual ~student();
private:
    int age;
    string name;
    string className;
};

student::student(student &stu)
{
    this->age = stu.age;
    this->className = stu.className;
    this->name = stu.name;
}

student::student(int age,string name,string className)
{
    this->age = age;
    this->name = name;
    this->className = className;
}

int student::getAge(){
    return this->age;
}

string student::getName(){
    return this->name;
}