12.14 使用shared_ptr编写connection

// Demo.cpp : Defines the entry point for the console application.
//

#include "stdafx.h"
#include <iostream>
#include <string>
#include <vector>
#include <memory>

using namespace std;

struct destination {
   const char *des;
};

struct connection {
   int ip;
};

connection connect(destination &d) {
   string des(d.des);
   int IP = stoi(des);
   connection c{ IP };
   return c;
}

void disconnect(connection &c) {
   c.ip = 0;
}

void end_connection(connection *cp) {
   cout << "Call disconnect to end connection" << endl;
   disconnect(*cp);
}

int main()
{
   destination d{ "102" };
   connection c = connect(d);
   shared_ptr<connection> p(&c, end_connection);
   // 使用lambda表达式
   // shared_ptr<connection> p(&c, [](connection *c) {cout << "end connection" << endl; (*c).ip = 0; });

   return 0;
}

注意end_connection的参数必须是指针类型，看起来shared_ptr在释放资源时，传递给deleter的是指针，所以必须接受指针参数。