實戰c++中的智能指針unique_ptr系列--通過unique_ptr對shared_ptr進行初始化

實戰c++中的智能指針unique_ptr系列--通過unique_ptr對shared_ptr進行初始化

首先需要明確的是，這篇文章不是要描述unique_ptr和shared_ptr兩個只能指針之間的區別，主要就是為了用unique_ptr對shared_ptr進行初始化。

#include 
#include 

int main()
{
    std::cout << "start!\n";
    auto customArrayAllocator = [](unsigned int num){
        std::cout << "custom array allocator\n";
        return new int[num];
    };

    std::cout << "allocator constructed\n";

    auto customArrayDeleter = [](int *ptr){
        std::cout << "custom array deleter\n";
        delete[] ptr;
    };

    std::cout << "deleter constructed\n";

    std::unique_ptr
        myUnique(customArrayAllocator(4), customArrayDeleter);

    std::cout << "unique_ptr constructed\n";

    std::shared_ptr
        myShared = std::move(myUnique);

    std::cout << "shared_ptr constructed\n";
}

輸出為：
start!
allocator constructed
deleter constructed
custom array allocator
unique_ptr constructed
shared_ptr constructed
custom array deleter

從輸出，通俗的講，就是unique的構造和刪除器都傳遞給了shared指針。

引用：
http://stackoverflow.com/questions/30495941/initialization-of-shared-ptrt-from-unique-ptrt?rq=1