[expected.bad]

# 22 General utilities library [[utilities]](./#utilities)

## 22.8 Expected objects [[expected]](expected#bad)

### 22.8.4 Class template bad_expected_access [expected.bad]

[🔗](#lib:bad_expected_access)

namespace std {template<class E>class bad_expected_access : public bad_expected_access<void> {public:constexpr explicit bad_expected_access(E); constexpr const char* what() const noexcept override; constexpr E& error() & noexcept; constexpr const E& error() const & noexcept; constexpr E&& error() && noexcept; constexpr const E&& error() const && noexcept; private: E *unex*; // *exposition only*};}

[1](#1)

[#](http://github.com/Eelis/draft/tree/9adde4bc1c62ec234483e63ea3b70a59724c745a/source/utilities.tex#L7918)

The class template bad_expected_access defines the type of objects thrown as exceptions to report the situation
where an attempt is made to access the value of an expected<T, E> object
for which has_value() is false[.](#1.sentence-1)

[🔗](#lib:bad_expected_access,constructor)

`constexpr explicit bad_expected_access(E e);
`

[2](#2)

[#](http://github.com/Eelis/draft/tree/9adde4bc1c62ec234483e63ea3b70a59724c745a/source/utilities.tex#L7930)

*Effects*: Initializes *unex* with std​::​move(e)[.](#2.sentence-1)

[🔗](#lib:error,bad_expected_access)

`constexpr const E& error() const & noexcept;
constexpr E& error() & noexcept;
`

[3](#3)

[#](http://github.com/Eelis/draft/tree/9adde4bc1c62ec234483e63ea3b70a59724c745a/source/utilities.tex#L7942)

*Returns*: *unex*[.](#3.sentence-1)

[🔗](#lib:error,bad_expected_access_)

`constexpr E&& error() && noexcept;
constexpr const E&& error() const && noexcept;
`

[4](#4)

[#](http://github.com/Eelis/draft/tree/9adde4bc1c62ec234483e63ea3b70a59724c745a/source/utilities.tex#L7954)

*Returns*: std​::​move(*unex*)[.](#4.sentence-1)

[🔗](#lib:what,bad_expected_access)

`constexpr const char* what() const noexcept override;
`

[5](#5)

[#](http://github.com/Eelis/draft/tree/9adde4bc1c62ec234483e63ea3b70a59724c745a/source/utilities.tex#L7965)

*Returns*: An implementation-defined ntbs,
which during constant evaluation is encoded with
the ordinary literal encoding ([[lex.ccon]](lex.ccon "5.13.3 Character literals"))[.](#5.sentence-1)