# 1.0.0[−][src]Enum core::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

`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);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: FnOnce() -> Ordering>(self, f: F) -> 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 Copy for Ordering` | [src]

###

`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 `!=`.

###

`impl Eq for Ordering` | [src]

###

`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 where Self: Sized,` | 1.21.0 [src]

Compares and returns the maximum of two values. Read more

####

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

Compares and returns the minimum of two values. 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 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 Hash for Ordering` | [src]

####

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

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

####

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

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

###

`impl Debug for Ordering` | [src]

####

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

Formats the value using the given formatter. Read more

## Auto Trait Implementations

###

`impl Send for Ordering` |

###

`impl Sync for Ordering` |

## Blanket Implementations

###

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

####

`fn into(Self) -> U` | [src]

Performs the conversion.

###

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

####

`fn from(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> 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(U) -> Result<T, <T as TryFrom<U>>::Error>` | [src]

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

Performs the conversion.

###

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

####

`fn borrow(&Self) -> &T` | [src]

Immutably borrows from an owned value. Read more

###

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

####

`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

# Help

## Keyboard Shortcuts

`?`
  Show this help dialog
`S`
  Focus the search field
`↑`
  Move up in search results
`↓`
  Move down in search results
`↹`
  Switch tab
`⏎`
  Go to active search result
`+`
  Expand all sections
`-`
  Collapse all sections

## Search Tricks

Prefix searches with a type followed by a colon (e.g., `fn:`) to restrict the search to a given type.

Accepted types are: `fn`, `mod`, `struct`, `enum`, `trait`, `type`, `macro`, and `const`.

Search functions by type signature (e.g., `vec -> usize` or `* -> vec`)

Search multiple things at once by splitting your query with comma (e.g., `str,u8` or `String,struct:Vec,test`)