C++: std::optional vs Smart Pointers

What are the main differences between std::optional and smart pointers in C++?

std::optional is used to represent an optional value, while smart pointers (like std::unique_ptr and std::shared_ptr) manage dynamic memory. std::optional is lightweight and doesn't own resources, whereas smart pointers ensure proper memory management.

When should I use std::optional instead of a smart pointer?

Use std::optional when you want to represent a value that may or may not be present without ownership semantics. Use smart pointers when you need to manage the lifetime of dynamically allocated objects.

Can you give an example of using std::optional?

Sure! Here's a simple example:

std::optional<int> findValue(int key) {
    if (keyExists(key)) {
        return getValue(key);
    }
    return std::nullopt;
}

This function returns an optional integer, indicating whether a value was found.

What are the performance implications of using std::optional?

std::optional is generally efficient, as it avoids heap allocation. However, if the contained type is large, copying it can be costly. In such cases, consider using std::optional with move semantics.