C++中值传递,引用传递,指针传递

#include <iostream>
using namespace std;

class tr{
    private:
        int i;
    public:
        tr(int n)
        {
            i = n;
        }
        void set(int n)
        {
            i = n;
        }
        int get()
        {
            return i;
        }
};
//以引用方式传递
#if 1
void sqr(tr &ob)
{
    ob.set(ob.get()*ob.get());
    cout<<"ob.i="<<ob.get()<<endl;

}
#endif

//以值方式传递
#if 0
void sqr(tr ob)
{
    ob.set(ob.get()*ob.get());
    cout<<"ob.i="<<ob.get()<<endl;

}
#endif

//以指针方式传递
#if 0
#define POINT
void sqr(tr *ob)
{

    ob->set(ob->get()*ob->get());
    cout<<"ob.i="<<ob->get()<<endl;

}
#endif
int main()
{
    tr obj(10);//定义一个类,并对其进行初始化
    #ifdef POINT
    sqr(&obj);
    #else
    sqr(obj);
    #endif
    cout<<"obj.i="<<obj.get()<<endl;

    return 0;
}