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C++ Smart Pointers
course content

Course Content

C++ Smart Pointers

C++ Smart Pointers

1. Introduction to Smart Pointers
Understanding PointersDynamic memory allocationThe Need For Smart Pointers
2. Unique Pointers
Introduction to Unique PointersMoving Unique PointersApplication For Unique PointersPassing Around Unique PointersMethods of a Unique Pointer
3. Shared Pointers
Introduction to Shared PointersCreating and Sharing Shared PointersCircular References and Shared Pointers
4. Weak Pointers
Introduction to Weak PointersCreating And Using Weak PointersBreaking Circular References With Weak PointersImportant Weak Pointer Functions
5. Advanced topics
Providing Custom Deleters For Smart PointersPerformance Considerations With Smart PointersOverview Shared vs Unique vs Weak Pointers

book
Circular References and Shared Pointers

When working with std::shared_ptr, you might encounter an issue known as a circular reference. A circular reference occurs when two objects hold shared_ptr references to each other. Since shared_ptr uses reference counting, the count never reaches zero, causing a memory leak.

cpp

main

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#include <iostream>
#include <memory>

class B; // Forward declaration

class A {
public:
    std::shared_ptr<B> p_b;
    ~A() { std::cout << "A destroyed\n"; }
};

class B {
public:
    ~B() { std::cout << "B destroyed\n"; }

    std::shared_ptr<A> p_a;
};

int main() 
{
    std::shared_ptr<A> a = std::make_shared<A>();
    std::shared_ptr<B> b = std::make_shared<B>();

    a->p_b = b;
    b->p_a = a;
}

There is a way to fix this issue you need to use a different type of smart pointer.

question mark

What problem does a circular reference cause in std::shared_ptr?

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Section 3. Chapter 3
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