C++20 STL Cookbook/

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Share Objects with std::shared_ptr

Share Objects with std::shared_ptr

Learn to share objects with std::shared_ptr.

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The std::shared_ptr class is a smart pointer that owns its managed object and maintains a use counter to keep track of copies. This recipe explores the use of shared_ptr to manage memory while sharing copies of the pointer.

Note: For more detail about smart pointers, see the introduction to the Manage allocated memory with std::unique_ptr recipe.

How to do it

In this recipe, we examine std::shared_ptr with a demonstration class that prints when its constructors and destructor are called:

  • First, we create a simple demonstration class:

struct Thing {
    string_view thname{ "unk" };
    Thing() {
        cout << format("default ctor: {}\n", thname);
    }
    Thing(const string_view& n) : thname(n) {
        cout << format("param ctor: {}\n", thname);
    }
    ~Thing() {
        cout << format("dtor: {}\n", thname);
    }
};

This ...