#[repr(i8)]pub enum Ordering {
Less = -1,
Equal = 0,
Greater = 1,
}
Expand description
An Ordering
is the result of a comparison between two values.
Examples
use std::cmp::Ordering;
assert_eq!(1.cmp(&2), Ordering::Less);
assert_eq!(1.cmp(&1), Ordering::Equal);
assert_eq!(2.cmp(&1), Ordering::Greater);
Variants§
Less = -1
An ordering where a compared value is less than another.
Equal = 0
An ordering where a compared value is equal to another.
Greater = 1
An ordering where a compared value is greater than another.
Implementations§
source§impl Ordering
impl Ordering
1.53.0 (const: 1.53.0) · sourcepub const fn is_eq(self) -> bool
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);
1.53.0 (const: 1.53.0) · sourcepub const fn is_ne(self) -> bool
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);
1.53.0 (const: 1.53.0) · sourcepub const fn is_lt(self) -> bool
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);
1.53.0 (const: 1.53.0) · sourcepub const fn is_gt(self) -> bool
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);
1.53.0 (const: 1.53.0) · sourcepub const fn is_le(self) -> bool
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);
1.53.0 (const: 1.53.0) · sourcepub const fn is_ge(self) -> bool
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);
const: 1.48.0 · sourcepub const fn reverse(self) -> Ordering
pub const fn reverse(self) -> Ordering
Reverses the Ordering
.
Less
becomesGreater
.Greater
becomesLess
.Equal
becomesEqual
.
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);
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);
1.17.0 (const: 1.48.0) · sourcepub const fn then(self, other: Ordering) -> Ordering
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);
1.17.0 · sourcepub fn then_with<F>(self, f: F) -> Ordering
pub fn then_with<F>(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);