👀 Views: 33 💬 Answers: 1 📅 Created: 2025-06-10

c++17 smart-pointers shared-ptr cpp

I'm a bit lost with I'm stuck on something that should probably be simple. I've been struggling with this for a few days now and could really use some help... I'm stuck on something that should probably be simple. I tried several approaches but none seem to work. I'm running into an scenario with `std::shared_ptr` in C++17 where the custom deleter I provided seems to be called multiple times under certain conditions. Here’s a snippet of the code that demonstrates the question: ```cpp #include <iostream> #include <memory> struct MyDeleter { void operator()(int* p) { std::cout << "Deleting integer: " << *p << '\n'; delete p; } }; int main() { std::shared_ptr<int> ptr1(new int(42), MyDeleter()); { std::shared_ptr<int> ptr2 = ptr1; std::cout << "Using value: " << *ptr2 << '\n'; } std::cout << "Exiting scope...\n"; return 0; } ``` When I run this code, I expect the integer to be deleted just once after both `ptr1` and `ptr2` go out of scope. However, the output shows that `MyDeleter` is called twice: ``` Using value: 42 Exiting scope... Deleting integer: 42 Deleting integer: 42 ``` I double-checked that I am using C++17 (g++ version 9.3.0), and I believe that I am correctly managing the ownership of the `shared_ptr`. I've also tried using `std::make_shared` to see if it resolves the scenario, but it leads to similar behavior. Could it be related to how the `shared_ptr` is being copied or the way the custom deleter is interacting with the reference counting? Any insights would be appreciated! My development environment is macOS. How would you solve this? Is there a better approach? I'd really appreciate any guidance on this. My team is using Cpp for this microservice. The project is a mobile app built with Cpp. I'm working in a Debian environment. I'm developing on Windows 11 with Cpp. This is my first time working with Cpp 3.9. Any feedback is welcome!