Enum std::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);

Run

Variants

Less

An ordering where a compared value is less than another.

Equal

An ordering where a compared value is equal to another.

Greater

An ordering where a compared value is greater than another.

Implementations

source

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);

Run

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);

Run

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);

Run

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);

Run

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);

Run

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);

Run

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);

Run

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);

Run

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);

Run

1.17.0 · source

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

Run

Trait Implementations

source

impl Clone for Ordering

source

fn clone(&self) -> Ordering

Returns a copy of the value. Read more

source

fn clone_from(&mut self, source: &Self)

Performs copy-assignment from source. Read more

source

impl Debug for Ordering

source

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

Formats the value using the given formatter. Read more

source

impl Hash for Ordering

source

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

Feeds this value into the given Hasher. Read more

1.3.0 · source

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

Feeds a slice of this type into the given Hasher. Read more

const: unstable · source

impl Ord for Ordering

const: unstable · source

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) -> Self

Compares and returns the maximum of two values. Read more

1.21.0 · source

fn min(self, other: Self) -> Self

Compares and returns the minimum of two values. Read more

1.50.0 · source

fn clamp(self, min: Self, max: Self) -> Self where
Self: PartialOrd<Self>,

Restrict a value to a certain interval. Read more

source

impl PartialEq<Ordering> for Ordering

source

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

This method tests for self and other values to be equal, and is used by ==. Read more

source

fn ne(&self, other: &Rhs) -> bool

This method tests for !=.

const: unstable · source

impl PartialOrd<Ordering> for Ordering

const: unstable · source

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

This method returns an ordering between self and other values if one exists. Read more

source

fn lt(&self, other: &Rhs) -> bool

This method tests less than (for self and other) and is used by the < operator. Read more

source

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

source

fn gt(&self, other: &Rhs) -> bool

This method tests greater than (for self and other) and is used by the > operator. Read more

source

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

source

impl Copy for Ordering

source

impl Eq for Ordering

source

impl StructuralEq for Ordering

source

impl StructuralPartialEq for Ordering