invalid use of member(did you forget the '&'?)是什么错误啊？？？

[elmnd]

#include <cstdlib>
#include <iostream>

using namespace std;

class point
{
    int x, y;
public:
    void set(int a, int b){x=a, y=b;}
    void print()const{cout<<"("<<x<<", "<<y<<")\n";}
    friend point operator + (const point &a, const point &b);
    friend point add(const point &a, const point &b);
};

point operator + (const point &a, const point &b)
{
    point s;
    s.set=(a.x+b.x, a.y+b.y);// 这里出错了
    return s;
}

point add(const point &a, const point &b)
{
    point s;
    s.set=(a.x+b.x, a.y+b.y);// 这里出错了
    return s;
}

int main(int argc, char *argv[])
{
    system("PAUSE");
    return EXIT_SUCCESS;
}

要怎样改哈？？

[brookmill]

多了个等号
s.set(a.x+b.x, a.y+b.y);

[lann64]

set只是个成员函数呀，你这样用，编译器去找成员变量，当然找不到了。

[xhs_lh04]

class point
{
int x, y;
public:
point():x(0),y(0){};
point(int a, int b):x(a),y(b){};
void set(int a, int b){x=a, y=b;}
void print()const{cout<<"("<<x<<", "<<y<<")\n";}
friend point operator + (const point &a, const point &b);
friend point add(const point &a, const point &b);
};