# Enum core::cmp::Ordering

1.0.0 · source ·
``````#[repr(i8)]
pub enum Ordering {
Less,
Equal,
Greater,
}``````
Expand description

An `Ordering` is the result of a comparison between two values.

## Examples

``````use std::cmp::Ordering;

let result = 1.cmp(&2);
assert_eq!(Ordering::Less, result);

let result = 1.cmp(&1);
assert_eq!(Ordering::Equal, result);

let result = 2.cmp(&1);
assert_eq!(Ordering::Greater, result);``````
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## Variants§

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### Less

An ordering where a compared value is less than another.

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### Equal

An ordering where a compared value is equal to another.

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### Greater

An ordering where a compared value is greater than another.

## Implementations§

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### impl Ordering

1.53.0 (const: 1.53.0) · source

#### pub const fn is_eq(self) -> bool

Returns `true` if the ordering is the `Equal` variant.

##### Examples
``````use std::cmp::Ordering;

assert_eq!(Ordering::Less.is_eq(), false);
assert_eq!(Ordering::Equal.is_eq(), true);
assert_eq!(Ordering::Greater.is_eq(), false);``````
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1.53.0 (const: 1.53.0) · source

#### pub const fn is_ne(self) -> bool

Returns `true` if the ordering is not the `Equal` variant.

##### Examples
``````use std::cmp::Ordering;

assert_eq!(Ordering::Less.is_ne(), true);
assert_eq!(Ordering::Equal.is_ne(), false);
assert_eq!(Ordering::Greater.is_ne(), true);``````
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1.53.0 (const: 1.53.0) · source

#### pub const fn is_lt(self) -> bool

Returns `true` if the ordering is the `Less` variant.

##### Examples
``````use std::cmp::Ordering;

assert_eq!(Ordering::Less.is_lt(), true);
assert_eq!(Ordering::Equal.is_lt(), false);
assert_eq!(Ordering::Greater.is_lt(), false);``````
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1.53.0 (const: 1.53.0) · source

#### pub const fn is_gt(self) -> bool

Returns `true` if the ordering is the `Greater` variant.

##### Examples
``````use std::cmp::Ordering;

assert_eq!(Ordering::Less.is_gt(), false);
assert_eq!(Ordering::Equal.is_gt(), false);
assert_eq!(Ordering::Greater.is_gt(), true);``````
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1.53.0 (const: 1.53.0) · source

#### pub const fn is_le(self) -> bool

Returns `true` if the ordering is either the `Less` or `Equal` variant.

##### Examples
``````use std::cmp::Ordering;

assert_eq!(Ordering::Less.is_le(), true);
assert_eq!(Ordering::Equal.is_le(), true);
assert_eq!(Ordering::Greater.is_le(), false);``````
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1.53.0 (const: 1.53.0) · source

#### pub const fn is_ge(self) -> bool

Returns `true` if the ordering is either the `Greater` or `Equal` variant.

##### Examples
``````use std::cmp::Ordering;

assert_eq!(Ordering::Less.is_ge(), false);
assert_eq!(Ordering::Equal.is_ge(), true);
assert_eq!(Ordering::Greater.is_ge(), true);``````
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const: 1.48.0 · source

#### pub const fn reverse(self) -> Ordering

Reverses the `Ordering`.

• `Less` becomes `Greater`.
• `Greater` becomes `Less`.
• `Equal` becomes `Equal`.
##### Examples

Basic behavior:

``````use std::cmp::Ordering;

assert_eq!(Ordering::Less.reverse(), Ordering::Greater);
assert_eq!(Ordering::Equal.reverse(), Ordering::Equal);
assert_eq!(Ordering::Greater.reverse(), Ordering::Less);``````
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This method can be used to reverse a comparison:

``````let data: &mut [_] = &mut [2, 10, 5, 8];

// sort the array from largest to smallest.
data.sort_by(|a, b| a.cmp(b).reverse());

let b: &mut [_] = &mut [10, 8, 5, 2];
assert!(data == b);``````
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1.17.0 (const: 1.48.0) · source

#### pub const fn then(self, other: Ordering) -> Ordering

Chains two orderings.

Returns `self` when it’s not `Equal`. Otherwise returns `other`.

##### Examples
``````use std::cmp::Ordering;

let result = Ordering::Equal.then(Ordering::Less);
assert_eq!(result, Ordering::Less);

let result = Ordering::Less.then(Ordering::Equal);
assert_eq!(result, Ordering::Less);

let result = Ordering::Less.then(Ordering::Greater);
assert_eq!(result, Ordering::Less);

let result = Ordering::Equal.then(Ordering::Equal);
assert_eq!(result, Ordering::Equal);

let x: (i64, i64, i64) = (1, 2, 7);
let y: (i64, i64, i64) = (1, 5, 3);
let result = x.0.cmp(&y.0).then(x.1.cmp(&y.1)).then(x.2.cmp(&y.2));

assert_eq!(result, Ordering::Less);``````
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1.17.0 · source

#### pub fn then_with<F: FnOnce() -> Ordering>(self, f: F) -> Ordering

Chains the ordering with the given function.

Returns `self` when it’s not `Equal`. Otherwise calls `f` and returns the result.

##### Examples
``````use std::cmp::Ordering;

let result = Ordering::Equal.then_with(|| Ordering::Less);
assert_eq!(result, Ordering::Less);

let result = Ordering::Less.then_with(|| Ordering::Equal);
assert_eq!(result, Ordering::Less);

let result = Ordering::Less.then_with(|| Ordering::Greater);
assert_eq!(result, Ordering::Less);

let result = Ordering::Equal.then_with(|| Ordering::Equal);
assert_eq!(result, Ordering::Equal);

let x: (i64, i64, i64) = (1, 2, 7);
let y: (i64, i64, i64) = (1, 5, 3);
let result = x.0.cmp(&y.0).then_with(|| x.1.cmp(&y.1)).then_with(|| x.2.cmp(&y.2));

assert_eq!(result, Ordering::Less);``````
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## Trait Implementations§

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### impl Clone for Ordering

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#### fn clone(&self) -> Ordering

Returns a copy of the value. Read more
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#### fn clone_from(&mut self, source: &Self)

Performs copy-assignment from `source`. Read more
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### impl Debug for Ordering

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#### fn fmt(&self, f: &mut Formatter<'_>) -> Result

Formats the value using the given formatter. Read more
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### impl Hash for Ordering

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#### fn hash<__H: Hasher>(&self, state: &mut __H)

Feeds this value into the given `Hasher`. Read more
1.3.0 · source§

#### fn hash_slice<H: Hasher>(data: &[Self], state: &mut H)where    Self: Sized,

Feeds a slice of this type into the given `Hasher`. Read more
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### impl Ord for Ordering

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#### const fn cmp(&self, other: &Ordering) -> Ordering

This method returns an `Ordering` between `self` and `other`. Read more
1.21.0 · source§

#### fn max(self, other: Self) -> Selfwhere    Self: Sized,

Compares and returns the maximum of two values. Read more
1.21.0 · source§

#### fn min(self, other: Self) -> Selfwhere    Self: Sized,

Compares and returns the minimum of two values. Read more
1.50.0 · source§

#### fn clamp(self, min: Self, max: Self) -> Selfwhere    Self: Sized + PartialOrd,

Restrict a value to a certain interval. Read more
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### impl PartialEq<Ordering> for Ordering

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#### const fn eq(&self, other: &Ordering) -> bool

This method tests for `self` and `other` values to be equal, and is used by `==`.
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#### fn ne(&self, other: &Rhs) -> bool

This method tests for `!=`. The default implementation is almost always sufficient, and should not be overridden without very good reason.
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### impl PartialOrd<Ordering> for Ordering

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#### const fn partial_cmp(&self, other: &Ordering) -> Option<Ordering>

This method returns an ordering between `self` and `other` values if one exists. Read more
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#### fn lt(&self, other: &Rhs) -> bool

This method tests less than (for `self` and `other`) and is used by the `<` operator. Read more
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#### fn le(&self, other: &Rhs) -> bool

This method tests less than or equal to (for `self` and `other`) and is used by the `<=` operator. Read more
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#### fn gt(&self, other: &Rhs) -> bool

This method tests greater than (for `self` and `other`) and is used by the `>` operator. Read more
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#### fn ge(&self, other: &Rhs) -> bool

This method tests greater than or equal to (for `self` and `other`) and is used by the `>=` operator. Read more
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## Blanket Implementations§

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### impl<T> Any for Twhere    T: 'static + ?Sized,

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#### fn type_id(&self) -> TypeId

Gets the `TypeId` of `self`. Read more
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### impl<T> Borrow<T> for Twhere    T: ?Sized,

const: unstable · source§

#### fn borrow(&self) -> &T

Immutably borrows from an owned value. Read more
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### impl<T> BorrowMut<T> for Twhere    T: ?Sized,

const: unstable · source§

#### fn borrow_mut(&mut self) -> &mut T

Mutably borrows from an owned value. Read more
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### impl<T> From<T> for T

const: unstable · source§

#### fn from(t: T) -> T

Returns the argument unchanged.

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### impl<T, U> Into<U> for Twhere    U: From<T>,

const: unstable · source§

#### fn into(self) -> U

Calls `U::from(self)`.

That is, this conversion is whatever the implementation of `From<T> for U` chooses to do.

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### impl<T, U> TryFrom<U> for Twhere    U: Into<T>,

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#### type Error = Infallible

The type returned in the event of a conversion error.
const: unstable · source§

#### fn try_from(value: U) -> Result<T, <T as TryFrom<U>>::Error>

Performs the conversion.
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### impl<T, U> TryInto<U> for Twhere    U: TryFrom<T>,

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#### type Error = <U as TryFrom<T>>::Error

The type returned in the event of a conversion error.
const: unstable · source§

#### fn try_into(self) -> Result<U, <U as TryFrom<T>>::Error>

Performs the conversion.
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