[logical.operations]

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

## 22.10 Function objects [[function.objects]](function.objects#logical.operations)

### 22.10.10 Logical operations [logical.operations]

#### [22.10.10.1](#general) General [[logical.operations.general]](logical.operations.general)

[1](#general-1)

[#](http://github.com/Eelis/draft/tree/9adde4bc1c62ec234483e63ea3b70a59724c745a/source/utilities.tex#L12796)

The library provides basic function object classes for all of the logical
operators in the language ([[expr.log.and]](expr.log.and "7.6.14 Logical AND operator"), [[expr.log.or]](expr.log.or "7.6.15 Logical OR operator"), [[expr.unary.op]](expr.unary.op "7.6.2.2 Unary operators"))[.](#general-1.sentence-1)

#### [22.10.10.2](#and) Class template logical_and [[logical.operations.and]](logical.operations.and)

[ð](#lib:logical_and)

`template<class T = void> struct logical_and {
  constexpr bool operator()(const T& x, const T& y) const;
};
`

[ð](#lib:operator(),logical_and)

`constexpr bool operator()(const T& x, const T& y) const;
`

[1](#and-1)

[#](http://github.com/Eelis/draft/tree/9adde4bc1c62ec234483e63ea3b70a59724c745a/source/utilities.tex#L12815)

*Returns*: x && y[.](#and-1.sentence-1)

[ð](#lib:logical_and%3c%3e)

`template<> struct logical_and<void> {
  template<class T, class U> constexpr auto operator()(T&& t, U&& u) const
    -> decltype(std::forward<T>(t) && std::forward<U>(u));

  using is_transparent = unspecified;
};
`

[ð](#lib:operator(),logical_and%3c%3e)

`template<class T, class U> constexpr auto operator()(T&& t, U&& u) const
    -> decltype(std::forward<T>(t) && std::forward<U>(u));
`

[2](#and-2)

[#](http://github.com/Eelis/draft/tree/9adde4bc1c62ec234483e63ea3b70a59724c745a/source/utilities.tex#L12837)

*Returns*: std​::​forward<T>(t) && std​::​forward<U>(u)[.](#and-2.sentence-1)

#### [22.10.10.3](#or) Class template logical_or [[logical.operations.or]](logical.operations.or)

[ð](#lib:logical_or)

`template<class T = void> struct logical_or {
  constexpr bool operator()(const T& x, const T& y) const;
};
`

[ð](#lib:operator(),logical_or)

`constexpr bool operator()(const T& x, const T& y) const;
`

[1](#or-1)

[#](http://github.com/Eelis/draft/tree/9adde4bc1c62ec234483e63ea3b70a59724c745a/source/utilities.tex#L12857)

*Returns*: x || y[.](#or-1.sentence-1)

[ð](#lib:logical_or%3c%3e)

`template<> struct logical_or<void> {
  template<class T, class U> constexpr auto operator()(T&& t, U&& u) const
    -> decltype(std::forward<T>(t) || std::forward<U>(u));

  using is_transparent = unspecified;
};
`

[ð](#lib:operator(),logical_or%3c%3e)

`template<class T, class U> constexpr auto operator()(T&& t, U&& u) const
    -> decltype(std::forward<T>(t) || std::forward<U>(u));
`

[2](#or-2)

[#](http://github.com/Eelis/draft/tree/9adde4bc1c62ec234483e63ea3b70a59724c745a/source/utilities.tex#L12879)

*Returns*: std​::​forward<T>(t) || std​::​forward<U>(u)[.](#or-2.sentence-1)

#### [22.10.10.4](#not) Class template logical_not [[logical.operations.not]](logical.operations.not)

[ð](#lib:logical_not)

`template<class T = void> struct logical_not {
  constexpr bool operator()(const T& x) const;
};
`

[ð](#lib:operator(),logical_not)

`constexpr bool operator()(const T& x) const;
`

[1](#not-1)

[#](http://github.com/Eelis/draft/tree/9adde4bc1c62ec234483e63ea3b70a59724c745a/source/utilities.tex#L12899)

*Returns*: !x[.](#not-1.sentence-1)

[ð](#lib:logical_not%3c%3e)

`template<> struct logical_not<void> {
  template<class T> constexpr auto operator()(T&& t) const
    -> decltype(!std::forward<T>(t));

  using is_transparent = unspecified;
};
`

[ð](#lib:operator(),logical_not%3c%3e)

`template<class T> constexpr auto operator()(T&& t) const
    -> decltype(!std::forward<T>(t));
`

[2](#not-2)

[#](http://github.com/Eelis/draft/tree/9adde4bc1c62ec234483e63ea3b70a59724c745a/source/utilities.tex#L12921)

*Returns*: !std​::​forward<T>(t)[.](#not-2.sentence-1)
