cppdraft_translate/cppdraft/optional/relops.md

[optional.relops]

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

## 22.5 Optional objects [[optional]](optional#relops)

### 22.5.7 Relational operators [optional.relops]

[🔗](#lib:operator==,optional)

`template<class T, class U> constexpr bool operator==(const optional<T>& x, const optional<U>& y);
`

[1](#1)

[#](http://github.com/Eelis/draft/tree/9adde4bc1c62ec234483e63ea3b70a59724c745a/source/utilities.tex#L5042)

*Constraints*: The expression *x == *y is well-formed and
its result is convertible to bool[.](#1.sentence-1)

[*Note [1](#note-1)*:

T need not be [*Cpp17EqualityComparable*](utility.arg.requirements#:Cpp17EqualityComparable "16.4.4.2 Template argument requirements [utility.arg.requirements]")[.](#1.sentence-2)

— *end note*]

[2](#2)

[#](http://github.com/Eelis/draft/tree/9adde4bc1c62ec234483e63ea3b70a59724c745a/source/utilities.tex#L5050)

*Returns*: If x.has_value() != y.has_value(), false; otherwise if x.has_value() == false, true; otherwise *x == *y[.](#2.sentence-1)

[3](#3)

[#](http://github.com/Eelis/draft/tree/9adde4bc1c62ec234483e63ea3b70a59724c745a/source/utilities.tex#L5054)

*Remarks*: Specializations of this function template
for which *x == *y is a core constant expression
are constexpr functions[.](#3.sentence-1)

[🔗](#lib:operator!=,optional)

`template<class T, class U> constexpr bool operator!=(const optional<T>& x, const optional<U>& y);
`

[4](#4)

[#](http://github.com/Eelis/draft/tree/9adde4bc1c62ec234483e63ea3b70a59724c745a/source/utilities.tex#L5067)

*Constraints*: The expression *x != *y is well-formed and
its result is convertible to bool[.](#4.sentence-1)

[5](#5)

[#](http://github.com/Eelis/draft/tree/9adde4bc1c62ec234483e63ea3b70a59724c745a/source/utilities.tex#L5072)

*Returns*: If x.has_value() != y.has_value(), true;
otherwise, if x.has_value() == false, false;
otherwise *x != *y[.](#5.sentence-1)

[6](#6)

[#](http://github.com/Eelis/draft/tree/9adde4bc1c62ec234483e63ea3b70a59724c745a/source/utilities.tex#L5078)

*Remarks*: Specializations of this function template
for which *x != *y is a core constant expression
are constexpr functions[.](#6.sentence-1)

[🔗](#lib:operator%3c,optional)

`template<class T, class U> constexpr bool operator<(const optional<T>& x, const optional<U>& y);
`

[7](#7)

[#](http://github.com/Eelis/draft/tree/9adde4bc1c62ec234483e63ea3b70a59724c745a/source/utilities.tex#L5091)

*Constraints*: *x < *y is well-formed
and its result is convertible to bool[.](#7.sentence-1)

[8](#8)

[#](http://github.com/Eelis/draft/tree/9adde4bc1c62ec234483e63ea3b70a59724c745a/source/utilities.tex#L5096)

*Returns*: If !y, false;
otherwise, if !x, true;
otherwise *x < *y[.](#8.sentence-1)

[9](#9)

[#](http://github.com/Eelis/draft/tree/9adde4bc1c62ec234483e63ea3b70a59724c745a/source/utilities.tex#L5102)

*Remarks*: Specializations of this function template
for which *x < *y is a core constant expression
are constexpr functions[.](#9.sentence-1)

[🔗](#lib:operator%3e,optional)

`template<class T, class U> constexpr bool operator>(const optional<T>& x, const optional<U>& y);
`

[10](#10)

[#](http://github.com/Eelis/draft/tree/9adde4bc1c62ec234483e63ea3b70a59724c745a/source/utilities.tex#L5115)

*Constraints*: The expression *x > *y is well-formed and
its result is convertible to bool[.](#10.sentence-1)

[11](#11)

[#](http://github.com/Eelis/draft/tree/9adde4bc1c62ec234483e63ea3b70a59724c745a/source/utilities.tex#L5120)

*Returns*: If !x, false;
otherwise, if !y, true;
otherwise *x > *y[.](#11.sentence-1)

[12](#12)

[#](http://github.com/Eelis/draft/tree/9adde4bc1c62ec234483e63ea3b70a59724c745a/source/utilities.tex#L5126)

*Remarks*: Specializations of this function template
for which *x > *y is a core constant expression
are constexpr functions[.](#12.sentence-1)

[🔗](#lib:operator%3c=,optional)

`template<class T, class U> constexpr bool operator<=(const optional<T>& x, const optional<U>& y);
`

[13](#13)

[#](http://github.com/Eelis/draft/tree/9adde4bc1c62ec234483e63ea3b70a59724c745a/source/utilities.tex#L5139)

*Constraints*: The expression *x <= *y is well-formed and
its result is convertible to bool[.](#13.sentence-1)

[14](#14)

[#](http://github.com/Eelis/draft/tree/9adde4bc1c62ec234483e63ea3b70a59724c745a/source/utilities.tex#L5144)

*Returns*: If !x, true;
otherwise, if !y, false;
otherwise *x <= *y[.](#14.sentence-1)

[15](#15)

[#](http://github.com/Eelis/draft/tree/9adde4bc1c62ec234483e63ea3b70a59724c745a/source/utilities.tex#L5150)

*Remarks*: Specializations of this function template
for which *x <= *y is a core constant expression
are constexpr functions[.](#15.sentence-1)

[🔗](#lib:operator%3e=,optional)

`template<class T, class U> constexpr bool operator>=(const optional<T>& x, const optional<U>& y);
`

[16](#16)

[#](http://github.com/Eelis/draft/tree/9adde4bc1c62ec234483e63ea3b70a59724c745a/source/utilities.tex#L5163)

*Constraints*: The expression *x >= *y is well-formed and
its result is convertible to bool[.](#16.sentence-1)

[17](#17)

[#](http://github.com/Eelis/draft/tree/9adde4bc1c62ec234483e63ea3b70a59724c745a/source/utilities.tex#L5168)

*Returns*: If !y, true;
otherwise, if !x, false;
otherwise *x >= *y[.](#17.sentence-1)

[18](#18)

[#](http://github.com/Eelis/draft/tree/9adde4bc1c62ec234483e63ea3b70a59724c745a/source/utilities.tex#L5174)

*Remarks*: Specializations of this function template
for which *x >= *y is a core constant expression
are constexpr functions[.](#18.sentence-1)

[🔗](#lib:operator%3c=%3e,optional)

`template<class T, [three_way_comparable_with](cmp.concept#concept:three_way_comparable_with "17.12.4 Concept three_­way_­comparable [cmp.concept]")<T> U>
  constexpr compare_three_way_result_t<T, U>
    operator<=>(const optional<T>& x, const optional<U>& y);
`

[19](#19)

[#](http://github.com/Eelis/draft/tree/9adde4bc1c62ec234483e63ea3b70a59724c745a/source/utilities.tex#L5189)

*Returns*: If x && y, *x <=> *y; otherwise x.has_value() <=> y.has_value()[.](#19.sentence-1)

[20](#20)

[#](http://github.com/Eelis/draft/tree/9adde4bc1c62ec234483e63ea3b70a59724c745a/source/utilities.tex#L5193)

*Remarks*: Specializations of this function template
for which *x <=> *y is a core constant expression
are constexpr functions[.](#20.sentence-1)