c++ 智能指针（转）

void SongVector()
{
    vector<unique_ptr<Song>> songs;

    // Create a few new unique_ptr<Song> instances
    // and add them to vector using implicit move semantics.
    songs.push_back(make_unique<Song>(L"B‘z", L"Juice"));
    songs.push_back(make_unique<Song>(L"Namie Amuro", L"Funky Town"));
    songs.push_back(make_unique<Song>(L"Kome Kome Club", L"Kimi ga Iru Dake de"));
    songs.push_back(make_unique<Song>(L"Ayumi Hamasaki", L"Poker Face"));

    // Pass by const reference when possible to avoid copying.
    for (const auto& song : songs)
    {
        wcout << L"Artist: " << song->artist << L"   Title: " << song->title << endl; 
    }    
}

class MyClass
{
private:
    // MyClass owns the unique_ptr.
    unique_ptr<ClassFactory> factory;
public:

    // Initialize by using make_unique with ClassFactory default constructor.
    MyClass() : factory ( make_unique<ClassFactory>())
    {
    }

    void MakeClass()
    {
        factory->DoSomething();
    }
};

// Create a unique_ptr to an array of 5 integers.
	auto p = make_unique<int[]>(5);

	// Initialize the array.
	for (int i = 0; i < 5; ++i)
	{
		p[i] = i;
		wcout << p[i] << endl;
	}

vector<shared_ptr<MediaAsset>> assets;

    assets.push_back(shared_ptr<Song>(new Song(L"Himesh Reshammiya", L"Tera Surroor")));
    assets.push_back(shared_ptr<Song>(new Song(L"Penaz Masani", L"Tu Dil De De")));
    assets.push_back(shared_ptr<Photo>(new Photo(L"2011-04-06", L"Redmond, WA", L"Soccer field at Microsoft.")));

    vector<shared_ptr<MediaAsset>> photos;

    copy_if(assets.begin(), assets.end(), back_inserter(photos), [] (shared_ptr<MediaAsset> p) -> bool
    {
        // Use dynamic_pointer_cast to test whether
        // element is a shared_ptr<Photo>.
        shared_ptr<Photo> temp = dynamic_pointer_cast<Photo>(p);		
        return temp.get() != nullptr;
    });

    for (const auto&  p : photos)
    {
        // We know that the photos vector contains only 
        // shared_ptr<Photo> objects, so use static_cast.
        wcout << "Photo location: " << (static_pointer_cast<Photo>(p))->location_ << endl;
    }

#include <iostream>
#include <memory>
#include <string>
#include <vector>
#include <algorithm>

using namespace std;

class Controller 
{
public:
    int Num;
    wstring Status;
    vector<weak_ptr<Controller>> others;
    explicit Controller(int i) : Num(i) , Status(L"On")
    {
        wcout << L"Creating Controller" << Num << endl;
    }

    ~Controller()
    {
        wcout << L"Destroying Controller" << Num << endl;
    }

    // Demonstrates how to test whether the  
    // pointed-to memory still exists or not. 
    void CheckStatuses() const
    {
        for_each(others.begin(), others.end(), [] (weak_ptr<Controller> wp)
        {
            try
            {
                auto p = wp.lock();
                wcout << L"Status of " << p->Num << " = " << p->Status << endl;
            }

            catch (bad_weak_ptr b)
            {
                wcout << L"Null object" << endl;
            }                
        });
    }
};

void RunTest()
{
    vector<shared_ptr<Controller>> v;

    v.push_back(shared_ptr<Controller>(new Controller(0)));
    v.push_back(shared_ptr<Controller>(new Controller(1)));
    v.push_back(shared_ptr<Controller>(new Controller(2)));
    v.push_back(shared_ptr<Controller>(new Controller(3)));
    v.push_back(shared_ptr<Controller>(new Controller(4)));

    // Each controller depends on all others not being deleted. 
    // Give each controller a pointer to all the others. 
    for (int i = 0 ; i < v.size(); ++i)
    {
        for_each(v.begin(), v.end(), [v,i] (shared_ptr<Controller> p)
        {
            if(p->Num != i)
            {
                v[i]->others.push_back(weak_ptr<Controller>(p));
                wcout << L"push_back to v[" << i << "]: " << p->Num << endl;
            }
        });        
    }

    for_each(v.begin(), v.end(), [](shared_ptr<Controller>& p)
    {
        wcout << L"use_count = " << p.use_count() << endl;
        p->CheckStatuses();
    });
}

int main()
{    
    RunTest(); 
    wcout << L"Press any key" << endl;
    char ch;
    cin.getline(&ch, 1);
}