Ordering in std::cmp - Rust (original) (raw)
Enum Ordering
1.0.0 · Source
#[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);§1.0.0
An ordering where a compared value is less than another.
§1.0.0
An ordering where a compared value is equal to another.
§1.0.0
An ordering where a compared value is greater than another.
1.53.0 (const: 1.53.0) · Source
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) · Source
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) · Source
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) · Source
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) · Source
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) · Source
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);1.0.0 (const: 1.48.0) · Source
Reverses the Ordering.
LessbecomesGreater.GreaterbecomesLess.EqualbecomesEqual.
§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) · Source
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 · Source
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);Tests for self and other values to be equal, and is used by ==.
Tests for !=. The default implementation is almost always sufficient, and should not be overridden without very good reason.
This method returns an ordering between self and other values if one exists. Read more
Tests less than (for self and other) and is used by the < operator. Read more
Tests less than or equal to (for self and other) and is used by the<= operator. Read more
Tests greater than (for self and other) and is used by the >operator. Read more
Tests greater than or equal to (for self and other) and is used by the >= operator. Read more