What are some examples of using shared_ptr in C++17?

Can you explain how to use shared_ptr in C++17?

Sure! In C++17, shared_ptr is a smart pointer that retains shared ownership of an object. When the last shared_ptr pointing to an object is destroyed, the object is deleted.

Can you give me a simple example?

Absolutely! Here's a basic example:

#include <iostream>
#include <memory>

int main() {
    std::shared_ptr<int> ptr1 = std::make_shared<int>(10);
    std::cout << "Value: " << *ptr1 << std::endl;
    {
        std::shared_ptr<int> ptr2 = ptr1; // ptr2 shares ownership
        std::cout << "Value from ptr2: " << *ptr2 << std::endl;
    } // ptr2 goes out of scope, but ptr1 still exists
    std::cout << "Value after ptr2 goes out of scope: " << *ptr1 << std::endl;
}

This code demonstrates how ptr1 and ptr2 share ownership of the integer.

What happens if I try to access ptr2 after it goes out of scope?

If you try to access ptr2 after it goes out of scope, it will lead to undefined behavior because ptr2 no longer exists. However, ptr1 will still be valid and can be used.

Are there any performance considerations with shared_ptr?

Yes, shared_ptr has some overhead due to reference counting. If performance is critical and you don't need shared ownership, consider using unique_ptr instead.