智能指针（19）

#ifndef
#define
#include <iostream>
using namespace std;

class A {
public:
  int a;
  int b;
  A(int a);
  A(int a, int b);
};

#endif

#include "A.h"

A::A(int a) {
  this->a = a;
  cout << "A::A(int a) a = " << this->a << endl;
}

A::A(int a, int b) {
  this->a = a;
  this->b = b;
  cout << "A::A(int a, int b) a = " << this->a << "  b = " << this->b <<endl;
}

#include "A.h"
#include <memory>

int main() {
  shared_ptr <A> p1 = make_shared<A>(1);
  shared_ptr <A> p2 = make_shared<A>(2, 3);

  cout << "p1->a = " << p1->a << endl;
  cout << "p2->a = " << p2->a << "   p2->b = " << p2->b << endl;

  return 0;
}

//既然这个程序有内存泄漏的风险，而我们平时有有可能忘记delete 那么有什么好办法呢？
//如果指针p有一个析构函数，该析构函数在p过期时候释放它指向的内存，那该多好~
//解决方案：我们引用 "智能指针"
//智能指针： 是行为类似于指针的类对象