# 1.0.0[−][src]Enum std::cmp::Ordering

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].

## Methods

`impl Ordering`

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`pub fn reverse(self) -> Ordering`

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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 mut 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

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

1.17.0[src]

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

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

F: FnOnce() -> Ordering,

1.17.0[src]

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

`impl Clone for Ordering`

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`fn clone(&self) -> Ordering`

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

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Performs copy-assignment from `source`

. Read more

`impl PartialOrd<Ordering> for Ordering`

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

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```
#[must_use]
fn lt(&self, other: &Rhs) -> bool
```

[src]

This method tests less than (for `self`

and `other`

) and is used by the `<`

operator. Read more

```
#[must_use]
fn le(&self, other: &Rhs) -> bool
```

[src]

This method tests less than or equal to (for `self`

and `other`

) and is used by the `<=`

operator. Read more

```
#[must_use]
fn gt(&self, other: &Rhs) -> bool
```

[src]

This method tests greater than (for `self`

and `other`

) and is used by the `>`

operator. Read more

```
#[must_use]
fn ge(&self, other: &Rhs) -> bool
```

[src]

This method tests greater than or equal to (for `self`

and `other`

) and is used by the `>=`

operator. Read more

`impl Ord for Ordering`

[src]

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

[src]

`fn max(self, other: Self) -> Self`

1.21.0[src]

Compares and returns the maximum of two values. Read more

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

1.21.0[src]

Compares and returns the minimum of two values. Read more

`impl Eq for Ordering`

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`impl PartialEq<Ordering> for Ordering`

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

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```
#[must_use]
fn ne(&self, other: &Rhs) -> bool
```

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This method tests for `!=`

.

`impl Debug for Ordering`

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`impl Hash for Ordering`

[src]

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

__H: Hasher,

[src]

__H: Hasher,

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

H: Hasher,

1.3.0[src]

H: Hasher,

Feeds a slice of this type into the given [`Hasher`

]. Read more

`impl Copy for Ordering`

[src]

## Auto Trait Implementations

## Blanket Implementations

`impl<T> From for T`

[src]

`impl<T, U> TryFrom for T where`

U: Into<T>,

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U: Into<T>,

`type Error = !`

The type returned in the event of a conversion error.

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

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`impl<T, U> TryInto for T where`

U: TryFrom<T>,

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U: TryFrom<T>,

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

The type returned in the event of a conversion error.

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

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`impl<T, U> Into for T where`

U: From<T>,

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U: From<T>,

`impl<T> Borrow for T where`

T: ?Sized,

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T: ?Sized,

`impl<T> BorrowMut for T where`

T: ?Sized,

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T: ?Sized,

#### ⓘImportant traits for &'_ mut I`fn borrow_mut(&mut self) -> &mut T`

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`impl<T> Any for T where`

T: 'static + ?Sized,

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T: 'static + ?Sized,

`impl<T> ToOwned for T where`

T: Clone,

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T: Clone,