👀 Views: 55 💬 Answers: 1 📅 Created: 2025-06-10

c++20 stdoptional debugging C++

I'm writing unit tests and I'm collaborating on a project where I'm experiencing unexpected behavior when using `std::optional` in C++20... I have a function that returns an `std::optional<int>`, and I want to reset its value based on certain conditions. However, it seems like the optional isn't being reset as I expected. Here's a simplified version of my code: ```cpp #include <iostream> #include <optional> std::optional<int> getValue(int condition) { if (condition > 0) { return condition; } return std::nullopt; } int main() { std::optional<int> value = getValue(10); std::cout << "Initial value: " << value.value() << '\n'; // Prints 10 value = getValue(-1); // Expecting this to reset the value std::cout << "After assignment: " << (value.has_value() ? std::to_string(value.value()) : "nullopt") << '\n'; // Expecting nullopt return 0; } ``` When I run this code, I expect `value` to be reset to `nullopt` after the assignment, but I'm still seeing the previous value when I print it. The output is: ``` Initial value: 10 After assignment: 10 ``` It seems like the assignment isn't working as intended. I've checked that I'm using C++20, and `getValue(-1)` should logically return `std::nullopt`. I've also tried adding a debug statement to print the state right after assignment but it doesn't help. Is there something I’m missing here? Is this a known behavior with `std::optional` that I need to account for, or am I doing something wrong with the assignment? I'm coming from a different tech stack and learning C++. I'd love to hear your thoughts on this. For reference, this is a production application. Any advice would be much appreciated.