这段代码运行不了是什么原因呢？

#include <iostream.h>

class point
{
    int x,y;
public:
    point(int x1=0,int y1=0):x(x1),y(y1){}      
    friend ostream& operator<<(ostream&, const point&);     
    friend istream& operator>>(istream&, point&);
};
ostream& operator<<(ostream& out, const point& src)
{
    out << '<' << src.x << ',' << src.y << '>' ;
    return out;
}

istream& operator>>(istream& in,point& target)
{
    in>> target.x >> target.y;
    return in;
}
int main()
{
    point a(1,2);
    cin>>a;
    cout<<a;
    return 0;
}

好像大部分 都是如此
 

#include<iostream>
using namespace std;
class point
{
    public:
        point(int px = 0, int py = 0):x(px), y(py){ //pass
        }
        friend ostream& operator << (ostream&, const point&);
        friend istream& operator >> (ostream&, point&);
    // private:
    public:
        int x;
        int y;
};

ostream& operator << (ostream& out, const point& src)
{
    out<< "< " <<src.x<< " , "<<src.y<< " >";
    return out;
}

istream& operator >>(istream& in, point& target)
{
    in >> target.x >>target.y;
    return in;
}
int main(int argc, char* argv[])
{
    int x, y;
    x = y = 3;
    point P(x, y);
    cin >> P; //输入: 3 8 (形式)
    cout << P;

}

我试过了，编译不过！你上面修改过的代码也运行不了！！

你的#include <iostream>改为#include <iostream.h>，把using namespace std;删除就能运行了，友元函数本来就能访问私有的数据成员，不必改为公有的。你是由于上面的错误编译器误报出不能访问私有成员。

“#include<iostream> using namespace std;”这是C++语言里的！！！“#include <iostream.h>”这是C语言

现在的VC++ .h加不加是一样的啦

头文件  c里的  找本简单的介绍c的书就会有的  执行头文件必用的  可以说是比较通用的一种命名

#include "iostream"
using namespace std;
class point
{int x,y;
public:
       point(int x1=0,int y1=0):x(x1),y(y1){}
       friend ostream& operator<<(ostream&, const point&);
       friend istream& operator>>(istream&,point&);
};
ostream& operator<<(ostream& out, const point& src)
{ cout<<'<'<<src.x<<','<<src.y<<'>';
return out;
}
istream& operator>>(istream& in,point& target)
{ cin>>target.x>>target.y;
return in;
}
int main()
{point a(1,2);
cout<<"请输入："<<endl;
cin>>a;
cout<<a;
return 0;
}
out和in编译器认识吗？cout,cin