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C++ Smart Pointers

bookBreaking Circular References With Weak Pointers

Weak pointers are designed to break circular references. By replacing a std::shared_ptr in a circular dependency with a std::weak_ptr, we prevent objects from unintentionally extending each other's lifetimes, allowing proper destruction.

main.cpp

main.cpp

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#include <iostream>
#include <memory>

class Node {
public:
    Node() { std::cout << "Node constructed." << std::endl; }
    ~Node() { std::cout << "Node destructed." << std::endl; }

    // A weak pointer to the next element prevents circular ownership.
    std::weak_ptr<Node> next;
};

int main() 
{
    // Creating three Node objects.
    std::shared_ptr<Node> node1 = std::make_shared<Node>();
    std::shared_ptr<Node> node2 = std::make_shared<Node>();
    std::shared_ptr<Node> node3 = std::make_shared<Node>();

    // Creating a list where the last node's next is a weak pointer
    node1->next = node2;
    node2->next = node3;
    node3->next = node1;
    // Now when node1, node2, and node3 go out of scope, their destructors will be called
}

The circular reference problem is resolved by changing next from a std::shared_ptr to a std::weak_ptr. Follow the comments in the code for a clearer understanding. Run the code to confirm that the destructors are now called properly no memory leaks!

question mark

The following code has two shared pointers A and B both sharing a resource. Modify it so that B becomes a weak pointer.

Select the correct answer

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Grazie per i tuoi commenti!

Sezione 4. Capitolo 3

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bookBreaking Circular References With Weak Pointers

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Weak pointers are designed to break circular references. By replacing a std::shared_ptr in a circular dependency with a std::weak_ptr, we prevent objects from unintentionally extending each other's lifetimes, allowing proper destruction.

main.cpp

main.cpp

copy

              
12345678910111213141516171819202122232425

            
#include <iostream>
#include <memory>

class Node {
public:
    Node() { std::cout << "Node constructed." << std::endl; }
    ~Node() { std::cout << "Node destructed." << std::endl; }

    // A weak pointer to the next element prevents circular ownership.
    std::weak_ptr<Node> next;
};

int main() 
{
    // Creating three Node objects.
    std::shared_ptr<Node> node1 = std::make_shared<Node>();
    std::shared_ptr<Node> node2 = std::make_shared<Node>();
    std::shared_ptr<Node> node3 = std::make_shared<Node>();

    // Creating a list where the last node's next is a weak pointer
    node1->next = node2;
    node2->next = node3;
    node3->next = node1;
    // Now when node1, node2, and node3 go out of scope, their destructors will be called
}

The circular reference problem is resolved by changing next from a std::shared_ptr to a std::weak_ptr. Follow the comments in the code for a clearer understanding. Run the code to confirm that the destructors are now called properly no memory leaks!

question mark

The following code has two shared pointers A and B both sharing a resource. Modify it so that B becomes a weak pointer.

Select the correct answer

Tutto è chiaro?

Come possiamo migliorarlo?

Grazie per i tuoi commenti!

Sezione 4. Capitolo 3
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