What are some use cases for std::shared_ptr in C++?

What are some use cases for std::shared_ptr in C++?

std::shared_ptr is useful for managing shared ownership of dynamically allocated objects. Common use cases include resource management in complex data structures, implementing observer patterns, and handling polymorphic types.

Can you give an example of using std::shared_ptr in a class?

Sure! Here's a simple example:

#include <iostream>
#include <memory>

class Resource {
public:
    Resource() { std::cout << "Resource acquired." << std::endl; }
    ~Resource() { std::cout << "Resource destroyed." << std::endl; }
};

class Manager {
public:
    std::shared_ptr<Resource> res;
    Manager() : res(std::make_shared<Resource>()) {}
};

int main() {
    Manager m1;
    {
        Manager m2 = m1; // m2 shares ownership of the Resource
    } // Resource is not destroyed here because m1 and m2 share it
    return 0;
}

In this example, both m1 and m2 share ownership of the Resource.

What are the advantages of using std::shared_ptr over raw pointers?

The main advantages of std::shared_ptr include automatic memory management, prevention of memory leaks, and easier handling of shared ownership. It also provides thread safety for shared access.

Are there any downsides to using std::shared_ptr?

Yes, some downsides include potential performance overhead due to reference counting, and the risk of circular references leading to memory leaks if not managed properly.