std::optional::operator->, std::optional::operator* - cppreference.com (original) (raw)

Accesses the contained value.

1,2) Returns a pointer to the contained value.

3-6) Returns a reference to the contained value.

[edit] Return value

5,6) std::move(*_[val](../optional.html#val "cpp/utility/optional")_ )

[edit] Notes

This operator does not check whether *this contains a value, users can do so manually by using has_value() or operator bool(). Alternatively, if checked access is needed, value() or value_or() may be used.

[edit] Example

#include #include #include #include   int main() { using namespace std::string_literals;   std::optional 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

[edit] Defect reports

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

[edit] See also

| | returns the contained value (public member function) [edit] | | ---------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------- | | | returns the contained value if available, another value otherwise (public member function) [edit] |