智能指针类的使用示例

今天学习了一下智能指针类的使用，想把学习的心得和大家分享一下，在用到智能指针的时候可以查阅和利用!代码如下：

#include<iostream>using namespace std;class Smart_Ptr{friend class Instance_Ptr;int *s_p;size_t count;Smart_Ptr(int *p): s_p(p),count(1) {}~Smart_Ptr() {delete s_p;}};class Instance_Ptr{public:Instance_Ptr(int *p,int i): ptr(new Smart_Ptr(p)),val(i) {}Instance_Ptr(const Instance_Ptr &orig):ptr(orig.ptr),val(orig.val){++ptr->count;}Instance_Ptr& operator=(const Instance_Ptr&);~Instance_Ptr(){if(--ptr->count==0) delete ptr;}int *get_ptr() const {return ptr->s_p;}int get_int() const {return val;}void set_ptr(int *p) {ptr->s_p=p;}void set_int(int i) {val=i;}int get_ptr_val() const {return *ptr->s_p;}void set_ptr_val(int i) {*ptr->s_p=i;}private:Smart_Ptr *ptr;int val;};Instance_Ptr& Instance_Ptr::operator=(const Instance_Ptr &rhs){++rhs.ptr->count;if(--ptr->count==0)delete ptr;ptr=rhs.ptr;val=rhs.val;return *this;}ostream& operator<<(ostream &os, const Instance_Ptr &hp){    os << "*ptr: " << hp.get_ptr_val() << "\t val: " << hp.get_int() << endl;    return os;}int main(){    int obj = 0;    Instance_Ptr ptr1(&obj, 12);    Instance_Ptr ptr2(ptr1);    cout << "(1) ptr1: " << ptr1 << endl << "ptr2: " << ptr2 << endl;    ptr1.set_ptr_val(12); // sets object to which both ptr1 and ptr2 point    ptr2.get_ptr_val();   // returns 12    cout << "(2) ptr1: " << ptr1 << endl << "ptr2: " << ptr2 << endl;    ptr1.set_int(2);   // changes s member only in ptr1    ptr2.get_int();    // returns 12    ptr1.get_int();    // returns 0    cout << "(3) ptr1: " << ptr1 << endl << "ptr2: " << ptr2 << endl;    return 0;}