/Rust

# Enum std::cmp::Ordering

```pub enum Ordering {
Less,
Equal,
Greater,
}```

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);```

## 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`[src]

#### `pub fn reverse(self) -> Ordering`[src]

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);```

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);```

#### `pub fn then(self, other: Ordering) -> Ordering`[src]1.17.0

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);```

#### `pub fn then_with<F>(self, f: F) -> Ordering where    F: FnOnce() -> Ordering, `[src]1.17.0

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);```

## Trait Implementations

### `impl Hash for Ordering`[src]

#### `fn hash_slice<H>(data: &[Self], state: &mut H) where    H: Hasher, `[src]1.3.0

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

### `impl Clone for Ordering`[src]

#### `fn clone_from(&mut self, source: &Self)`[src]

Performs copy-assignment from `source`. Read more

### `impl PartialOrd<Ordering> for Ordering`[src]

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

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

#### `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

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

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

#### `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 max(self, other: Self) -> Self`[src]1.21.0

Compares and returns the maximum of two values. Read more

#### `fn min(self, other: Self) -> Self`[src]1.21.0

Compares and returns the minimum of two values. Read more

#### `fn clamp(self, min: Self, max: Self) -> Self`[src]

🔬 This is a nightly-only experimental API. (clamp #44095)

Restrict a value to a certain interval. Read more

### `impl PartialEq<Ordering> for Ordering`[src]

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

This method tests for `!=`.

## Blanket Implementations

### `impl<T, U> TryFrom<U> for T where    U: Into<T>, `[src]

#### `type Error = Infallible`

The type returned in the event of a conversion error.

### `impl<T, U> TryInto<U> for T where    U: TryFrom<T>, `[src]

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

The type returned in the event of a conversion error.

### `impl<T> Borrow<T> for T where    T: ?Sized, `[src]

ⓘImportant traits for &'_ mut F
```impl<'_, F> Future for &'_ mut F where
F: Unpin + Future + ?Sized,
type Output = <F as Future>::Output;
impl<'_, I> Iterator for &'_ mut I where
I: Iterator + ?Sized,
type Item = <I as Iterator>::Item;
impl<'_, W: Write + ?Sized> Write for &'_ mut W
```

### `impl<T> BorrowMut<T> for T where    T: ?Sized, `[src]

ⓘImportant traits for &'_ mut F
```impl<'_, F> Future for &'_ mut F where
F: Unpin + Future + ?Sized,
type Output = <F as Future>::Output;
impl<'_, I> Iterator for &'_ mut I where
I: Iterator + ?Sized,
type Item = <I as Iterator>::Item;
impl<'_, W: Write + ?Sized> Write for &'_ mut W
```

### `impl<T> ToOwned for T where    T: Clone, `[src]

#### `type Owned = T`

The resulting type after obtaining ownership.

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