std::option...::operator*(3)

💅 NAME 💅

hey bestie, welcome to the std::option...::operator*(3) page from the C++ Standard Libary manual ✨. Your faves are std::optional::operator->,std::optional::operator* - std::optional::operator->,std::optional::operator*. Yes, the page really does say it twice — iconic behavior, no notes 💅.

---

✨ Synopsis ✨

okay so here's the whole signature situation, copied exactly:

constexpr const T* operator->() const noexcept;   (1) (since C++17)
constexpr T* operator->() noexcept;               (1) (since C++17)
constexpr const T& operator*() const& noexcept;   (2) (since C++17)
constexpr T& operator*() & noexcept;              (2) (since C++17)
constexpr const T&& operator*() const&& noexcept; (2) (since C++17)
constexpr T&& operator*() && noexcept;            (2) (since C++17)

Accesses the contained value.

1. Returns a pointer to the contained value.
2. Returns a reference to the contained value.

⚠️ The behavior is undefined if *this does not contain a value. Like, actually undefined — do not play with that, bestie 😭.

---

🎀 Parameters 🎀

Absolutely none, babe: (none).

---

💖 Return value 💖

Pointer or reference to the contained value. That's it, that's the whole vibe 🫶.

---

🧠 Notes 🧠

🚨 This operator does not check whether the optional contains a value!

You can do so manually by using has_value() or simply operator bool(). Alternatively, if checked access is needed, value() or value_or() may be used. Slay 💅.

---

🌸 Example 🌸

run this code, bestie:

// Run this code

#include <iomanip>
#include <iostream>
#include <optional>
#include <string>

int main()
{
    using namespace std::string_literals;

    std::optional<int> opt1 = 1;
    std::cout << "opt1: " << *opt1 << '\n';

    *opt1 = 2;
    std::cout << "opt1: " << *opt1 << '\n';

    std::optional<std::string> opt2 = "abc"s;
    std::cout << "opt2: " << std::quoted(*opt2) << ", size: " <<
        opt2->size() << '\n';

    // You can "take" the contained value by calling operator* on an rvalue to optional

    auto taken = *std::move(opt2);
    std::cout << "taken: " << std::quoted(taken) << "\n"
                 "opt2: " << std::quoted(*opt2) << ", size: " <<
        opt2->size()  << '\n';
}

💫 Output 💫

opt1: 1
opt1: 2
opt2: "abc", size: 3
taken: "abc"
opt2: "", size: 0

---

🩹 Defect reports 🩹

The following behavior-changing defect reports were applied retroactively to previously published C++ standards.

• DR: LWG 2762
• Applied to: C++17
• Behavior as published: operator-> and operator* might be potentially-throwing
• Correct behavior: made noexcept

periodt 🫡.

---

👀 See also 👀

• value — returns the contained value (public member function)
• value_or — returns the contained value if available, another value otherwise (public member function)

---

mwah 💋 cute little footer moment: source/version http://cppreference.com, date 2024.06.10, and this has been the std::option...::operator*(3) page from the C++ Standard Libary manual. bye bestie 🫶🎀✨