[cmp.weakord]

# 17 Language support library [[support]](./#support)

## 17.12 Comparisons [[cmp]](cmp#weakord)

### 17.12.2 Comparison category types [[cmp.categories]](cmp.categories#cmp.weakord)

#### 17.12.2.3 Class weak_ordering [cmp.weakord]

[1](#1)

[#](http://github.com/Eelis/draft/tree/9adde4bc1c62ec234483e63ea3b70a59724c745a/source/support.tex#L5019)

The weak_ordering type is typically used
as the result type of a three-way comparison operator ([[expr.spaceship]](expr.spaceship "7.6.8 Three-way comparison operator"))
for a type that admits
all of the six two-way comparison operators ([[expr.rel]](expr.rel "7.6.9 Relational operators"), [[expr.eq]](expr.eq "7.6.10 Equality operators"))
and for which equality need not imply substitutability[.](#1.sentence-1)

[🔗](#lib:weak_ordering)

namespace std {class weak_ordering {int *value*; // *exposition only*// exposition-only constructorsconstexpr explicit weak_ordering(*ord* v) noexcept : *value*(int(v)) {} // *exposition only*public:// valid valuesstatic const weak_ordering less; static const weak_ordering equivalent; static const weak_ordering greater; // conversionsconstexpr operator partial_ordering() const noexcept; // comparisonsfriend constexpr bool operator==(weak_ordering v, *unspecified*) noexcept; friend constexpr bool operator==(weak_ordering v, weak_ordering w) noexcept = default; friend constexpr bool operator< (weak_ordering v, *unspecified*) noexcept; friend constexpr bool operator> (weak_ordering v, *unspecified*) noexcept; friend constexpr bool operator<=(weak_ordering v, *unspecified*) noexcept; friend constexpr bool operator>=(weak_ordering v, *unspecified*) noexcept; friend constexpr bool operator< (*unspecified*, weak_ordering v) noexcept; friend constexpr bool operator> (*unspecified*, weak_ordering v) noexcept; friend constexpr bool operator<=(*unspecified*, weak_ordering v) noexcept; friend constexpr bool operator>=(*unspecified*, weak_ordering v) noexcept; friend constexpr weak_ordering operator<=>(weak_ordering v, *unspecified*) noexcept; friend constexpr weak_ordering operator<=>(*unspecified*, weak_ordering v) noexcept; }; // valid values' definitionsinline constexpr weak_ordering weak_ordering::less(*ord*::*less*); inline constexpr weak_ordering weak_ordering::equivalent(*ord*::*equivalent*); inline constexpr weak_ordering weak_ordering::greater(*ord*::*greater*);}

[🔗](#lib:operator_partial_ordering,weak_ordering)

`constexpr operator partial_ordering() const noexcept;
`

[2](#2)

[#](http://github.com/Eelis/draft/tree/9adde4bc1c62ec234483e63ea3b70a59724c745a/source/support.tex#L5075)

*Returns*: *value* == 0 ? partial_ordering::equivalent :*value* < 0 ? partial_ordering::less : partial_ordering::greater

[🔗](#lib:operator==,weak_ordering)

`constexpr bool operator==(weak_ordering v, unspecified) noexcept;
constexpr bool operator< (weak_ordering v, unspecified) noexcept;
constexpr bool operator> (weak_ordering v, unspecified) noexcept;
constexpr bool operator<=(weak_ordering v, unspecified) noexcept;
constexpr bool operator>=(weak_ordering v, unspecified) noexcept;
`

[3](#3)

[#](http://github.com/Eelis/draft/tree/9adde4bc1c62ec234483e63ea3b70a59724c745a/source/support.tex#L5098)

*Returns*: v.*value* @ 0 for operator@[.](#3.sentence-1)

[🔗](#lib:operator%3c,weak_ordering_)

`constexpr bool operator< (unspecified, weak_ordering v) noexcept;
constexpr bool operator> (unspecified, weak_ordering v) noexcept;
constexpr bool operator<=(unspecified, weak_ordering v) noexcept;
constexpr bool operator>=(unspecified, weak_ordering v) noexcept;
`

[4](#4)

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

*Returns*: 0 @ v.*value* for operator@[.](#4.sentence-1)

[🔗](#lib:operator%3c=%3e,weak_ordering)

`constexpr weak_ordering operator<=>(weak_ordering v, unspecified) noexcept;
`

[5](#5)

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

*Returns*: v[.](#5.sentence-1)

[🔗](#lib:operator%3c=%3e,weak_ordering_)

`constexpr weak_ordering operator<=>(unspecified, weak_ordering v) noexcept;
`

[6](#6)

[#](http://github.com/Eelis/draft/tree/9adde4bc1c62ec234483e63ea3b70a59724c745a/source/support.tex#L5137)

*Returns*: v < 0 ? weak_ordering​::​greater : v > 0 ? weak_ordering​::​less : v[.](#6.sentence-1)