# 1.0.0[−][src]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);Run```

## Variants

An ordering where a compared value is less [than another].

An ordering where a compared value is equal [to another].

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);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]

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 Hash for Ordering`[src]

#### `fn hash<__H>(&self, state: &mut __H) where    __H: Hasher, `[src]

Feeds this value into the given [`Hasher`]. Read more

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

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

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

#### `fn clone(&self) -> Ordering`[src]

Returns a copy of the value. Read more

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

Performs copy-assignment from `source`. Read more

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

#### `fn partial_cmp(&self, other: &Ordering) -> Option<Ordering>`[src]

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

#### ```#[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]

This method returns an `Ordering` between `self` and `other`. Read more

#### `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 Debug for Ordering`[src]

#### `fn fmt(&self, f: &mut Formatter) -> Result<(), Error>`[src]

Formats the value using the given formatter. Read more

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

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

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

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

This method tests for `!=`.

## Blanket Implementations

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

#### `type Error = !`

🔬 This is a nightly-only experimental API. (`try_from `#33417)

The type returned in the event of a conversion error.

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

🔬 This is a nightly-only experimental API. (`try_from `#33417)

Performs the conversion.

### `impl<T> From for T`[src]

#### `fn from(t: T) -> T`[src]

Performs the conversion.

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

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

🔬 This is a nightly-only experimental API. (`try_from `#33417)

The type returned in the event of a conversion error.

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

🔬 This is a nightly-only experimental API. (`try_from `#33417)

Performs the conversion.

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

#### `fn into(self) -> U`[src]

Performs the conversion.

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

#### ⓘImportant traits for &'a mut I### Important traits for &'a mut I `impl<'a, I> Iterator for &'a mut I where    I: Iterator + ?Sized,  type Item = <I as Iterator>::Item;impl<'a, R: Read + ?Sized> Read for &'a mut Rimpl<'a, W: Write + ?Sized> Write for &'a mut W``fn borrow(&self) -> &T`[src]

Immutably borrows from an owned value. Read more

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

#### ⓘImportant traits for &'a mut I### Important traits for &'a mut I `impl<'a, I> Iterator for &'a mut I where    I: Iterator + ?Sized,  type Item = <I as Iterator>::Item;impl<'a, R: Read + ?Sized> Read for &'a mut Rimpl<'a, W: Write + ?Sized> Write for &'a mut W``fn borrow_mut(&mut self) -> &mut T`[src]

Mutably borrows from an owned value. Read more

### `impl<T> Any for T where    T: 'static + ?Sized, `[src]

#### `fn get_type_id(&self) -> TypeId`[src]

🔬 This is a nightly-only experimental API. (`get_type_id `#27745)

this method will likely be replaced by an associated static

Gets the `TypeId` of `self`. Read more

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

#### `fn to_owned(&self) -> T`[src]

Creates owned data from borrowed data, usually by cloning. Read more

#### `fn clone_into(&self, target: &mut T)`[src]

🔬 This is a nightly-only experimental API. (`toowned_clone_into `#41263)