NAME¶

std::optional::operator->,std::optional::operator* - std::optional::operator->,std::optional::operator*

Synopsis¶

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.

Parameters¶

(none)

Return value¶

Pointer or reference to the contained value.

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.

Example¶

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

See also¶

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