STL學習筆記(六) 仿寫的 不完整的autoptr類

#include <iostream>using namespace std;//可以自動釋放動態分配的記憶體template <typename T>class autoptr{T* p;public:autoptr(T* p=NULL):p(p){}~autoptr(){delete p;}autoptr(autoptr&a){p = a.p;a.p = NULL;}autoptr& operator=(autoptr& a){if(this == &a) return *this; //拷貝建構函式中要主要的問題： 拷貝自己p = a.p;a.p = NULL;return *this;}T& operator*(){return *p;}T* operator->(){return p;}};class A{int data;public:A(int d):data(d){ cout << "A()" << endl;}~A(){cout << "~A()" << endl;}void show(){cout << this  << ' ' <<data << endl;}};int main(){autoptr<A> p(new A(10));p->show();autoptr<A> q(p);q->show();}