std::cmp::Ord - Rust
Description: API documentation for the Rust `Ord` trait in crate `std`.
Keywords: rust, rustlang, rust-lang, Ord

# Trait std::cmp::Ord 1.0.0 [−] [src]

    pub trait Ord: Eq + PartialOrd<Self> {
        fn cmp(&self, other: &Self) -> Ordering;

        fn max(self, other: Self) -> Self { ... }
        fn min(self, other: Self) -> Self { ... }
    }

Trait for types that form a total order.

An order is a total order if it is (for all `a`, `b` and `c`):

- total and antisymmetric: exactly one of `a < b`, `a == b` or `a > b` is true; and
- transitive, `a < b` and `b < c` implies `a < c`. The same must hold for both `==` and `>`.

## Derivable

This trait can be used with `#[derive]`. When `derive`d on structs, it will produce a lexicographic ordering based on the top-to-bottom declaration order of the struct's members. When `derive`d on enums, variants are ordered by their top-to-bottom declaration order.

## How can I implement `Ord`?

`Ord` requires that the type also be `PartialOrd` and `Eq` (which requires `PartialEq`).

Then you must define an implementation for `cmp()`. You may find it useful to use `cmp()` on your type's fields.

Implementations of `PartialEq`, `PartialOrd`, and `Ord` must agree with each other. It's easy to accidentally make them disagree by deriving some of the traits and manually implementing others.

Here's an example where you want to sort people by height only, disregarding `id` and `name`:

    use std::cmp::Ordering;

    #[derive(Eq)]
    struct Person {
        id: u32,
        name: String,
        height: u32,
    }

    impl Ord for Person {
        fn cmp(&self, other: &Person) -> Ordering {
            self.height.cmp(&other.height)
        }
    }

    impl PartialOrd for Person {
        fn partial_cmp(&self, other: &Person) -> Option<Ordering> {
            Some(self.cmp(other))
        }
    }

    impl PartialEq for Person {
        fn eq(&self, other: &Person) -> bool {
            self.height == other.height
        }
    }Run

## Required Methods

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

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

By convention, `self.cmp(&other)` returns the ordering matching the expression `self <operator> other` if true.

# Examples

    use std::cmp::Ordering;

    assert_eq!(5.cmp(&10), Ordering::Less);
    assert_eq!(10.cmp(&5), Ordering::Greater);
    assert_eq!(5.cmp(&5), Ordering::Equal);Run

## Provided Methods

### `fn max(self, other: Self) -> Self`
1.21.0

Compares and returns the maximum of two values.

Returns the second argument if the comparison determines them to be equal.

# Examples

    assert_eq!(2, 1.max(2));
    assert_eq!(2, 2.max(2));Run

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

Compares and returns the minimum of two values.

Returns the first argument if the comparison determines them to be equal.

# Examples

    assert_eq!(1, 1.min(2));
    assert_eq!(2, 2.min(2));Run

## Implementations on Foreign Types

### `impl<T> Ord for NonZero<T> where
T: Zeroable + Ord,`
[src]

#### `fn cmp(&self, __arg_0: &NonZero<T>) -> Ordering`
[src]

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

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

## Implementors

- [src]
  `impl<T> Ord for LinkedList<T> where
  T: Ord,`
- [src]
  `impl<T> Ord for Rc<T> where
  T: Ord + ?Sized,`
- [src]
  `impl Ord for String`
- [src]
  `impl<T> Ord for Vec<T> where
  T: Ord,`
- [src]
  `impl<'a, B> Ord for Cow<'a, B> where
  B: Ord + ToOwned + ?Sized,`
- [src]
  `impl<K, V> Ord for BTreeMap<K, V> where
  K: Ord,
  V: Ord,`
- [src]
  `impl<A> Ord for VecDeque<A> where
  A: Ord,`
- [src]
  `impl<T> Ord for Arc<T> where
  T: Ord + ?Sized,`
- [src]
  `impl<T> Ord for Box<T> where
  T: Ord + ?Sized,`
- [src]
  `impl<T> Ord for BTreeSet<T> where
  T: Ord,`
- [src]
  `impl<T> Ord for [T; 22] where
  T: Ord,`
- [src]
  `impl<A, B, C, D> Ord for (A, B, C, D) where
  A: Ord,
  B: Ord,
  C: Ord,
  D: Ord + ?Sized,`
- [src]
  `impl Ord for u16`
- [src]
  `impl Ord for bool`
- [src]
  `impl<T> Ord for [T; 5] where
  T: Ord,`
- [src]
  `impl<A, B, C, D, E, F, G, H, I, J> Ord for (A, B, C, D, E, F, G, H, I, J) where
  A: Ord,
  B: Ord,
  C: Ord,
  D: Ord,
  E: Ord,
  F: Ord,
  G: Ord,
  H: Ord,
  I: Ord,
  J: Ord + ?Sized,`
- [src]
  `impl<Ret, A, B> Ord for unsafe fn(A, B) -> Ret`
- [src]
  `impl<Ret, A, B, C, D, E, F> Ord for unsafe extern "C" fn(A, B, C, D, E, F, ...) -> Ret`
- [src]
  `impl<T> Ord for PhantomData<T> where
  T: ?Sized,`
- [src]
  `impl<Ret, A, B, C, D, E> Ord for extern "C" fn(A, B, C, D, E) -> Ret`
- [src]
  `impl<Ret, A> Ord for fn(A) -> Ret`
- [src]
  `impl<T> Ord for *mut T where
  T: ?Sized,`
- [src]
  `impl Ord for i128`
- [src]
  `impl<T> Ord for [T; 32] where
  T: Ord,`
- [src]
  `impl<T> Ord for [T; 26] where
  T: Ord,`
- [src]
  `impl<T> Ord for [T; 20] where
  T: Ord,`
- [src]
  `impl<T> Ord for [T; 30] where
  T: Ord,`
- [src]
  `impl<Ret> Ord for unsafe fn() -> Ret`
- [src]
  `impl<Ret> Ord for unsafe extern "C" fn() -> Ret`
- [src]
  `impl Ord for i32`
- [src]
  `impl Ord for NoneError`
- [src]
  `impl<T> Ord for Cell<T> where
  T: Copy + Ord,`
- [src]
  `impl<T> Ord for [T; 3] where
  T: Ord,`
- [src]
  `impl<Ret, A, B, C, D, E, F, G, H, I> Ord for unsafe extern "C" fn(A, B, C, D, E, F, G, H, I, ...) -> Ret`
- [src]
  `impl<Ret, A, B, C, D, E, F, G> Ord for extern "C" fn(A, B, C, D, E, F, G, ...) -> Ret`
- [src]
  `impl<Ret> Ord for extern "C" fn() -> Ret`
- [src]
  `impl<Ret, A, B, C, D> Ord for unsafe extern "C" fn(A, B, C, D) -> Ret`
- [src]
  `impl<Ret, A, B, C, D, E, F, G, H, I, J, K, L> Ord for unsafe fn(A, B, C, D, E, F, G, H, I, J, K, L) -> Ret`
- [src]
  `impl<Ret, A, B, C, D, E, F> Ord for unsafe extern "C" fn(A, B, C, D, E, F) -> Ret`
- [src]
  `impl<A> Ord for (A,) where
  A: Ord + ?Sized,`
- [src]
  `impl<A, B, C, D, E, F, G, H> Ord for (A, B, C, D, E, F, G, H) where
  A: Ord,
  B: Ord,
  C: Ord,
  D: Ord,
  E: Ord,
  F: Ord,
  G: Ord,
  H: Ord + ?Sized,`
- [src]
  `impl<Ret, A> Ord for unsafe extern "C" fn(A) -> Ret`
- [src]
  `impl<T> Ord for [T; 8] where
  T: Ord,`
- [src]
  `impl<T> Ord for Wrapping<T> where
  T: Ord,`
- [src]
  `impl<T> Ord for [T; 13] where
  T: Ord,`
- [src]
  `impl<Ret, A, B, C, D> Ord for unsafe extern "C" fn(A, B, C, D, ...) -> Ret`
- [src]
  `impl<A, B, C> Ord for (A, B, C) where
  A: Ord,
  B: Ord,
  C: Ord + ?Sized,`
- [src]
  `impl Ord for u32`
- [src]
  `impl Ord for ()`
- [src]
  `impl<Ret, A, B, C, D, E, F, G, H, I, J> Ord for extern "C" fn(A, B, C, D, E, F, G, H, I, J) -> Ret`
- [src]
  `impl<Ret, A, B, C, D, E, F, G, H> Ord for extern "C" fn(A, B, C, D, E, F, G, H) -> Ret`
- [src]
  `impl Ord for Ordering`
- [src]
  `impl<'a, A> Ord for &'a mut A where
  A: Ord + ?Sized,`
- [src]
  `impl<Ret, A, B> Ord for extern "C" fn(A, B, ...) -> Ret`
- [src]
  `impl Ord for u128`
- [src]
  `impl<T> Ord for [T; 1] where
  T: Ord,`
- [src]
  `impl<T> Ord for [T; 4] where
  T: Ord,`
- [src]
  `impl Ord for !`
- [src]
  `impl<Ret, A, B> Ord for fn(A, B) -> Ret`
- [src]
  `impl<Ret, A, B, C> Ord for fn(A, B, C) -> Ret`
- [src]
  `impl<A, B, C, D, E, F, G, H, I, J, K> Ord for (A, B, C, D, E, F, G, H, I, J, K) where
  A: Ord,
  B: Ord,
  C: Ord,
  D: Ord,
  E: Ord,
  F: Ord,
  G: Ord,
  H: Ord,
  I: Ord,
  J: Ord,
  K: Ord + ?Sized,`
- [src]
  `impl<A, B, C, D, E, F, G> Ord for (A, B, C, D, E, F, G) where
  A: Ord,
  B: Ord,
  C: Ord,
  D: Ord,
  E: Ord,
  F: Ord,
  G: Ord + ?Sized,`
- [src]
  `impl<Ret, A, B, C, D, E, F, G, H> Ord for unsafe fn(A, B, C, D, E, F, G, H) -> Ret`
- [src]
  `impl<Ret, A, B, C, D, E, F> Ord for unsafe fn(A, B, C, D, E, F) -> Ret`
- [src]
  `impl<A, B, C, D, E, F, G, H, I, J, K, L> Ord for (A, B, C, D, E, F, G, H, I, J, K, L) where
  A: Ord,
  B: Ord,
  C: Ord,
  D: Ord,
  E: Ord,
  F: Ord,
  G: Ord,
  H: Ord,
  I: Ord,
  J: Ord,
  K: Ord,
  L: Ord + ?Sized,`
- [src]
  `impl<T> Ord for [T; 9] where
  T: Ord,`
- [src]
  `impl<T> Ord for *const T where
  T: ?Sized,`
- [src]
  `impl<Ret, A, B, C, D, E, F, G, H> Ord for unsafe extern "C" fn(A, B, C, D, E, F, G, H, ...) -> Ret`
- [src]
  `impl<Ret, A, B, C, D, E, F> Ord for extern "C" fn(A, B, C, D, E, F) -> Ret`
- [src]
  `impl<A, B, C, D, E, F, G, H, I> Ord for (A, B, C, D, E, F, G, H, I) where
  A: Ord,
  B: Ord,
  C: Ord,
  D: Ord,
  E: Ord,
  F: Ord,
  G: Ord,
  H: Ord,
  I: Ord + ?Sized,`
- [src]
  `impl<Ret, A, B, C, D, E, F, G, H, I> Ord for fn(A, B, C, D, E, F, G, H, I) -> Ret`
- [src]
  `impl<Ret, A, B, C> Ord for extern "C" fn(A, B, C, ...) -> Ret`
- [src]
  `impl<T> Ord for [T; 16] where
  T: Ord,`
- [src]
  `impl<Ret, A, B, C, D, E, F, G, H, I, J> Ord for fn(A, B, C, D, E, F, G, H, I, J) -> Ret`
- [src]
  `impl<'a, A> Ord for &'a A where
  A: Ord + ?Sized,`
- [src]
  `impl<T> Ord for [T; 7] where
  T: Ord,`
- [src]
  `impl<Ret, A, B, C, D, E, F, G, H, I, J, K, L> Ord for extern "C" fn(A, B, C, D, E, F, G, H, I, J, K, L) -> Ret`
- [src]
  `impl<Ret, A> Ord for unsafe extern "C" fn(A, ...) -> Ret`
- [src]
  `impl<Ret, A, B, C> Ord for unsafe extern "C" fn(A, B, C) -> Ret`
- [src]
  `impl<T> Ord for [T; 27] where
  T: Ord,`
- [src]
  `impl<Ret, A, B, C, D, E, F, G, H, I> Ord for unsafe fn(A, B, C, D, E, F, G, H, I) -> Ret`
- [src]
  `impl<T> Ord for [T; 29] where
  T: Ord,`
- [src]
  `impl<T> Ord for ManuallyDrop<T> where
  T: Ord,`
- [src]
  `impl<T> Ord for [T; 21] where
  T: Ord,`
- [src]
  `impl<T> Ord for [T; 24] where
  T: Ord,`
- [src]
  `impl<Ret, A, B, C, D, E, F, G, H, I> Ord for extern "C" fn(A, B, C, D, E, F, G, H, I, ...) -> Ret`
- [src]
  `impl<Ret, A, B, C, D, E, F, G, H, I, J, K> Ord for extern "C" fn(A, B, C, D, E, F, G, H, I, J, K, ...) -> Ret`
- [src]
  `impl<Ret, A, B, C, D> Ord for fn(A, B, C, D) -> Ret`
- [src]
  `impl Ord for i16`
- [src]
  `impl<Ret, A, B, C, D, E, F, G, H, I, J, K> Ord for unsafe fn(A, B, C, D, E, F, G, H, I, J, K) -> Ret`
- [src]
  `impl<T> Ord for [T; 2] where
  T: Ord,`
- [src]
  `impl<Ret, A, B, C, D, E> Ord for unsafe extern "C" fn(A, B, C, D, E) -> Ret`
- [src]
  `impl<T> Ord for [T; 25] where
  T: Ord,`
- [src]
  `impl<T> Ord for [T; 12] where
  T: Ord,`
- [src]
  `impl<Ret, A, B, C, D, E, F, G, H> Ord for fn(A, B, C, D, E, F, G, H) -> Ret`
- [src]
  `impl<Ret, A, B, C> Ord for unsafe fn(A, B, C) -> Ret`
- [src]
  `impl<Ret, A, B, C, D, E, F, G, H, I, J, K, L> Ord for extern "C" fn(A, B, C, D, E, F, G, H, I, J, K, L, ...) -> Ret`
- [src]
  `impl<T> Ord for [T; 23] where
  T: Ord,`
- [src]
  `impl Ord for i8`
- [src]
  `impl<Ret, A, B, C, D, E, F, G, H, I, J> Ord for unsafe extern "C" fn(A, B, C, D, E, F, G, H, I, J, ...) -> Ret`
- [src]
  `impl<Ret, A, B, C, D, E, F, G> Ord for extern "C" fn(A, B, C, D, E, F, G) -> Ret`
- [src]
  `impl<Ret, A, B, C, D, E, F, G, H, I, J, K> Ord for unsafe extern "C" fn(A, B, C, D, E, F, G, H, I, J, K) -> Ret`
- [src]
  `impl<T> Ord for [T; 18] where
  T: Ord,`
- [src]
  `impl<Ret, A, B, C, D, E, F, G, H, I, J> Ord for extern "C" fn(A, B, C, D, E, F, G, H, I, J, ...) -> Ret`
- [src]
  `impl<Ret, A, B, C, D, E, F, G> Ord for unsafe extern "C" fn(A, B, C, D, E, F, G, ...) -> Ret`
- [src]
  `impl<Ret, A, B, C, D> Ord for unsafe fn(A, B, C, D) -> Ret`
- [src]
  `impl Ord for Error`
- [src]
  `impl<Ret, A, B, C, D, E, F, G, H, I, J, K, L> Ord for unsafe extern "C" fn(A, B, C, D, E, F, G, H, I, J, K, L, ...) -> Ret`
- [src]
  `impl<A, B, C, D, E, F> Ord for (A, B, C, D, E, F) where
  A: Ord,
  B: Ord,
  C: Ord,
  D: Ord,
  E: Ord,
  F: Ord + ?Sized,`
- [src]
  `impl Ord for u64`
- [src]
  `impl<Ret, A, B, C> Ord for extern "C" fn(A, B, C) -> Ret`
- [src]
  `impl<T> Ord for [T; 0] where
  T: Ord,`
- [src]
  `impl Ord for TypeId`
- [src]
  `impl<Ret, A, B, C, D, E, F, G, H, I, J> Ord for unsafe fn(A, B, C, D, E, F, G, H, I, J) -> Ret`
- [src]
  `impl<Ret, A, B, C, D, E, F, G, H> Ord for extern "C" fn(A, B, C, D, E, F, G, H, ...) -> Ret`
- [src]
  `impl<Ret, A, B, C, D, E, F, G> Ord for unsafe extern "C" fn(A, B, C, D, E, F, G) -> Ret`
- [src]
  `impl<Ret, A, B> Ord for extern "C" fn(A, B) -> Ret`
- [src]
  `impl<Ret, A, B, C, D, E> Ord for fn(A, B, C, D, E) -> Ret`
- [src]
  `impl<Ret, A, B, C, D, E, F> Ord for extern "C" fn(A, B, C, D, E, F, ...) -> Ret`
- [src]
  `impl<Ret, A, B, C, D, E, F, G> Ord for unsafe fn(A, B, C, D, E, F, G) -> Ret`
- [src]
  `impl<Ret, A, B> Ord for unsafe extern "C" fn(A, B) -> Ret`
- [src]
  `impl<T> Ord for [T; 15] where
  T: Ord,`
- [src]
  `impl Ord for i64`
- [src]
  `impl<Ret, A, B, C, D, E, F, G, H, I, J, K, L> Ord for fn(A, B, C, D, E, F, G, H, I, J, K, L) -> Ret`
- [src]
  `impl<Ret, A, B, C> Ord for unsafe extern "C" fn(A, B, C, ...) -> Ret`
- [src]
  `impl<T, E> Ord for Result<T, E> where
  E: Ord,
  T: Ord,`
- [src]
  `impl<T> Ord for [T; 14] where
  T: Ord,`
- [src]
  `impl<Ret, A, B, C, D, E, F, G, H, I, J, K> Ord for fn(A, B, C, D, E, F, G, H, I, J, K) -> Ret`
- [src]
  `impl<Ret, A, B> Ord for unsafe extern "C" fn(A, B, ...) -> Ret`
- [src]
  `impl<Ret, A, B, C, D, E, F, G> Ord for fn(A, B, C, D, E, F, G) -> Ret`
- [src]
  `impl<Ret, A, B, C, D, E, F, G, H, I> Ord for unsafe extern "C" fn(A, B, C, D, E, F, G, H, I) -> Ret`
- [src]
  `impl<T> Ord for [T; 31] where
  T: Ord,`
- [src]
  `impl<T> Ord for [T] where
  T: Ord,`
- [src]
  `impl<Ret, A, B, C, D, E, F, G, H, I> Ord for extern "C" fn(A, B, C, D, E, F, G, H, I) -> Ret`
- [src]
  `impl<Y, R> Ord for GeneratorState<Y, R> where
  R: Ord,
  Y: Ord,`
- [src]
  `impl<Ret, A, B, C, D, E> Ord for unsafe fn(A, B, C, D, E) -> Ret`
- [src]
  `impl<Ret, A, B, C, D, E, F> Ord for fn(A, B, C, D, E, F) -> Ret`
- [src]
  `impl Ord for u8`
- [src]
  `impl<Ret, A> Ord for extern "C" fn(A) -> Ret`
- [src]
  `impl Ord for str`
- [src]
  `impl<Ret, A> Ord for extern "C" fn(A, ...) -> Ret`
- [src]
  `impl Ord for isize`
- [src]
  `impl<T> Ord for [T; 19] where
  T: Ord,`
- [src]
  `impl<Ret, A> Ord for unsafe fn(A) -> Ret`
- [src]
  `impl<T> Ord for Reverse<T> where
  T: Ord,`
- [src]
  `impl<Ret> Ord for fn() -> Ret`
- [src]
  `impl<A, B> Ord for (A, B) where
  A: Ord,
  B: Ord + ?Sized,`
- [src]
  `impl<T> Ord for [T; 6] where
  T: Ord,`
- [src]
  `impl<Ret, A, B, C, D, E> Ord for extern "C" fn(A, B, C, D, E, ...) -> Ret`
- [src]
  `impl<Ret, A, B, C, D> Ord for extern "C" fn(A, B, C, D) -> Ret`
- [src]
  `impl<Ret, A, B, C, D, E, F, G, H> Ord for unsafe extern "C" fn(A, B, C, D, E, F, G, H) -> Ret`
- [src]
  `impl<T> Ord for [T; 28] where
  T: Ord,`
- [src]
  `impl<Ret, A, B, C, D, E> Ord for unsafe extern "C" fn(A, B, C, D, E, ...) -> Ret`
- [src]
  `impl<Ret, A, B, C, D> Ord for extern "C" fn(A, B, C, D, ...) -> Ret`
- [src]
  `impl<Ret, A, B, C, D, E, F, G, H, I, J, K, L> Ord for unsafe extern "C" fn(A, B, C, D, E, F, G, H, I, J, K, L) -> Ret`
- [src]
  `impl<Ret, A, B, C, D, E, F, G, H, I, J, K> Ord for unsafe extern "C" fn(A, B, C, D, E, F, G, H, I, J, K, ...) -> Ret`
- [src]
  `impl Ord for usize`
- [src]
  `impl<T> Ord for [T; 11] where
  T: Ord,`
- [src]
  `impl Ord for char`
- [src]
  `impl<Ret, A, B, C, D, E, F, G, H, I, J, K> Ord for extern "C" fn(A, B, C, D, E, F, G, H, I, J, K) -> Ret`
- [src]
  `impl<Ret, A, B, C, D, E, F, G, H, I, J> Ord for unsafe extern "C" fn(A, B, C, D, E, F, G, H, I, J) -> Ret`
- [src]
  `impl Ord for Infallible`
- [src]
  `impl<T> Ord for [T; 10] where
  T: Ord,`
- [src]
  `impl<A, B, C, D, E> Ord for (A, B, C, D, E) where
  A: Ord,
  B: Ord,
  C: Ord,
  D: Ord,
  E: Ord + ?Sized,`
- [src]
  `impl<T> Ord for RefCell<T> where
  T: Ord + ?Sized,`
- [src]
  `impl<T> Ord for [T; 17] where
  T: Ord,`
- [src]
  `impl<T> Ord for Option<T> where
  T: Ord,`
- [src]
  `impl Ord for UnicodeVersion`
- [src]
  `impl Ord for CString`
- [src]
  `impl Ord for CStr`
- [src]
  `impl Ord for OsString`
- [src]
  `impl Ord for OsStr`
- [src]
  `impl Ord for ErrorKind`
- [src]
  `impl Ord for IpAddr`
- [src]
  `impl Ord for Ipv4Addr`
- [src]
  `impl Ord for Ipv6Addr`
- [src]
  `impl<'a> Ord for Prefix<'a>`
- [src]
  `impl<'a> Ord for PrefixComponent<'a>`
- [src]
  `impl<'a> Ord for Component<'a>`
- [src]
  `impl<'a> Ord for Components<'a>`
- [src]
  `impl Ord for PathBuf`
- [src]
  `impl Ord for Path`
- [src]
  `impl Ord for Duration`
- [src]
  `impl Ord for Instant`
- [src]
  `impl Ord for SystemTime`

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