C++ 中封装的含义和简单实现方式

#include <iostream>
 
using std::cout;
using std::endl;
 
typedef struct complex
{
    int x;
    int y;
}COMP;
 
void init(COMP &tmp,int x,int y)
{
    tmp.x = x;
    tmp.y = y;
}
 
COMP * operator +(COMP &tmp1,COMP &tmp2)
{
    COMP *p = static_cast<COMP *>(new COMP);
    p->x = tmp1.x + tmp2.x;
    p->y = tmp1.y + tmp2.y;
    return p;
}
 
COMP * operator -(COMP &tmp1,COMP &tmp2)
{
    COMP *p = static_cast<COMP *>(new COMP);
    p->x = tmp1.x - tmp2.x;
    p->y = tmp1.y - tmp2.y;
    return p;
}
 
COMP * operator *(COMP &tmp1,COMP &tmp2)
{
    COMP *p = static_cast<COMP *>(new COMP);
    p->x = tmp1.x*tmp2.x - tmp1.y*tmp2.y;
    p->y = tmp1.x*tmp2.y + tmp1.y*tmp2.x;
    return p;
}
 
int main()
{
    COMP x,y;
    init(x,1,2);
    init(y,3,4);
    cout<<x.x<<" "<<x.y<<endl;
    cout<<y.x<<" "<<y.y<<endl;
 
    COMP *z;
    z = x+y;
    cout<<z->x<<" "<<z->y<<endl;
    delete z;
 
    z = x-y;
    cout<<z->x<<" "<<z->y<<endl;
    delete z;
 
    z = x*y;
    cout<<z->x<<" "<<z->y<<endl;
    delete z;
 
    return 0;
}

#include <iostream>
 
using std::cout;
using std::endl;
 
class complex
{
public:
    complex()
    {
        this->x = 0;
        this->y = 0;
    }
 
    complex(int x, int y):x(x),y(y){}
 
    complex * operator +(complex &tmp)
    {
        complex *p = static_cast<complex *>(new complex);
        p->x = this->x + tmp.x;
        p->y = this->y + tmp.y;
        return p;
    }
 
    complex * operator -(complex &tmp)
    {
        complex *p = static_cast<complex *>(new complex);
        p->x = this->x - tmp.x;
        p->y = this->y - tmp.y;
        return p;
    }
 
    complex * operator *(complex &tmp)
    {
        complex *p = static_cast<complex *>(new complex);
        p->x = this->x*tmp.x - this->y*tmp.y;
        p->y = this->x*tmp.y + this->y*tmp.x;
        return p;
    }
 
    void display()
    {
        cout<<this->x<<" "<<this->y<<endl;
    }
 
private:
    int x;
    int y;
};
 
 
int main()
{
    complex x(1,2),y(3,4);
    x.display();
    y.display();
 
    complex *z;
    z = x+y;
    z->display();
    delete z;
 
    z = x-y;
    z->display();
    delete z;
 
    z = x*y;
    z->display();
    delete z;
 
    return 0;
}