my_auto_ptr通过它的析构函数来调用delete删除某对象的指针，来达到自动释放内存，而不需要显示的调用delete某对象。
（1）实现自动释放
#include <iostream>
#include <string>
using namespace std;
struct People
{
public:
People() {cout << "People" << endl;}
~People() {cout << "~People" << endl;}
void run(void) const {cout << "Peple can run!" << endl;}
};
class my_auto_ptr
{
public:
my_auto_ptr(People* p) : p(p) {}
~my_auto_ptr() {delete p;}
private:
People* p;
};
int main(int argc, char *argv[])
{
my_auto_ptr ptr(new People);
return 0;
}
程序输出：
People
~People
（2）实现调用该对象的成员
#include <iostream>
#include <string>
using namespace std;
struct People
{
public:
People() {cout << "People" << endl;}
~People() {cout << "~People" << endl;}
void run(void) const {cout << "Peple can run!" << endl;}
};
class my_auto_ptr
{
public:
my_auto_ptr(People* p) : p(p) {}
~my_auto_ptr() {delete p;}
People* operator->() const {cout << "->" << endl; return p;}
const People& operator*() const {cout << "*" << endl; return *p;}
const People* operator&() const {cout << "&" << endl; return p;}
private:
People* p;
};
int main(int argc, char *argv[])
{
my_auto_ptr ptr(new People);
ptr->run();
(*ptr).run();
&ptr;
return 0;
}
/*
总结：
ptr->run();
这里ptr是一个my_auto_ptr对象，p->run的含义与(p.operator->())->run求值相同。
p.operator->()返回对People对象的指针，然后对返回的People调用run()函数。
*/
程序输出：
People
->
Peple can run!
*
Peple can run!
&
~People
（3）实现泛型版本
#include <iostream>
#include <string>
using namespace std;
struct People
{
public:
People() {cout << "People" << endl;}
~People() {cout << "~People" << endl;}
void run(void) const {cout << "Peple can run!" << endl;}
};
class Student {};
template<typename T>
class my_auto_ptr
{
public:
my_auto_ptr(T* p) : p(p) {}
~my_auto_ptr() {delete p;}
T* operator->() const {cout << "->" << endl; return p;}
const T& operator*() const {cout << "*" << endl; return *p;}
private:
T* p;
};
int main(int argc, char *argv[])
{
my_auto_ptr<People> ptr1(new People);
my_auto_ptr<Student> ptr2(new Student);
return 0;
}
