```
pub trait Ord: Eq + PartialOrd {
// Required method
fn cmp(&self, other: &Self) -> Ordering;
// Provided methods
fn max(self, other: Self) -> Self
where Self: Sized { ... }
fn min(self, other: Self) -> Self
where Self: Sized { ... }
fn clamp(self, min: Self, max: Self) -> Self
where Self: Sized + PartialOrd { ... }
}
```

## Expand description

Trait for types that form a total order.

Implementations must be consistent with the `PartialOrd`

implementation, and ensure
`max`

, `min`

, and `clamp`

are consistent with `cmp`

:

`partial_cmp(a, b) == Some(cmp(a, b))`

.`max(a, b) == max_by(a, b, cmp)`

(ensured by the default implementation).`min(a, b) == min_by(a, b, cmp)`

(ensured by the default implementation).- For
`a.clamp(min, max)`

, see the method docs (ensured by the default implementation).

It’s easy to accidentally make `cmp`

and `partial_cmp`

disagree by
deriving some of the traits and manually implementing others.

Violating these requirements is a logic error. The behavior resulting from a logic error is not
specified, but users of the trait must ensure that such logic errors do *not* result in
undefined behavior. This means that `unsafe`

code **must not** rely on the correctness of these
methods.

### §Corollaries

From the above and the requirements of `PartialOrd`

, it follows that for
all `a`

, `b`

and `c`

:

- exactly one of
`a < b`

,`a == b`

or`a > b`

is true; and `<`

is transitive:`a < b`

and`b < c`

implies`a < c`

. The same must hold for both`==`

and`>`

.

Mathematically speaking, the `<`

operator defines a strict weak order. In
cases where `==`

conforms to mathematical equality, it also defines a
strict total order.

### §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 primarily by their discriminants.
Secondarily, they are ordered by their fields.
By default, the discriminant is smallest for variants at the top, and
largest for variants at the bottom. Here’s an example:

```
#[derive(PartialEq, Eq, PartialOrd, Ord)]
enum E {
Top,
Bottom,
}
assert!(E::Top < E::Bottom);
```

However, manually setting the discriminants can override this default behavior:

```
#[derive(PartialEq, Eq, PartialOrd, Ord)]
enum E {
Top = 2,
Bottom = 1,
}
assert!(E::Bottom < E::Top);
```

### §Lexicographical comparison

Lexicographical comparison is an operation with the following properties:

- Two sequences are compared element by element.
- The first mismatching element defines which sequence is lexicographically less or greater than the other.
- If one sequence is a prefix of another, the shorter sequence is lexicographically less than the other.
- If two sequences have equivalent elements and are of the same length, then the sequences are lexicographically equal.
- An empty sequence is lexicographically less than any non-empty sequence.
- Two empty sequences are lexicographically equal.

### §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.

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: &Self) -> Ordering {
self.height.cmp(&other.height)
}
}
impl PartialOrd for Person {
fn partial_cmp(&self, other: &Self) -> Option<Ordering> {
Some(self.cmp(other))
}
}
impl PartialEq for Person {
fn eq(&self, other: &Self) -> bool {
self.height == other.height
}
}
```

## Required Methods§

1.0.0 · source#### fn cmp(&self, other: &Self) -> Ordering

#### 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);
```

## Provided Methods§

1.21.0 · source#### fn max(self, other: Self) -> Selfwhere
Self: Sized,

#### fn max(self, other: Self) -> Selfwhere
Self: Sized,

Compares and returns the maximum of two values.

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

##### §Examples

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

1.21.0 · source#### fn min(self, other: Self) -> Selfwhere
Self: Sized,

#### fn min(self, other: Self) -> Selfwhere
Self: Sized,

Compares and returns the minimum of two values.

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

##### §Examples

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

1.50.0 · source#### fn clamp(self, min: Self, max: Self) -> Selfwhere
Self: Sized + PartialOrd,

#### fn clamp(self, min: Self, max: Self) -> Selfwhere
Self: Sized + PartialOrd,

## Object Safety§

**not**object safe.

## Implementors§

### impl Ord for ErrorReplyReason

### impl Ord for ExecutionError

### impl Ord for ExtError

### impl Ord for MemoryError

### impl Ord for MessageError

### impl Ord for ReplyCode

### impl Ord for ReservationError

### impl Ord for SignalCode

### impl Ord for SimpleExecutionError

### impl Ord for SimpleProgramCreationError

### impl Ord for SuccessReplyReason

### impl Ord for AsciiChar

### impl Ord for Ordering

### impl Ord for Infallible

### impl Ord for IpAddr

### impl Ord for SocketAddr

### impl Ord for bool

### impl Ord for char

### impl Ord for i8

### impl Ord for i16

### impl Ord for i32

### impl Ord for i64

### impl Ord for i128

### impl Ord for isize

### impl Ord for !

### impl Ord for str

Implements ordering of strings.

Strings are ordered lexicographically by their byte values. This orders Unicode code
points based on their positions in the code charts. This is not necessarily the same as
“alphabetical” order, which varies by language and locale. Sorting strings according to
culturally-accepted standards requires locale-specific data that is outside the scope of
the `str`

type.

### impl Ord for u8

### impl Ord for u16

### impl Ord for u32

### impl Ord for u64

### impl Ord for u128

### impl Ord for ()

### impl Ord for usize

### impl Ord for SyscallError

### impl Ord for ActorId

### impl Ord for CodeId

### impl Ord for MessageId

### impl Ord for Percent

### impl Ord for ReservationId

### impl Ord for MetaType

### impl Ord for TypeId

### impl Ord for CStr

### impl Ord for CString

### impl Ord for Error

### impl Ord for CpuidResult

### impl Ord for Ipv4Addr

### impl Ord for Ipv6Addr

### impl Ord for SocketAddrV4

### impl Ord for SocketAddrV6

### impl Ord for ATerm

### impl Ord for B0

### impl Ord for B1

### impl Ord for Z0

### impl Ord for Equal

### impl Ord for Greater

### impl Ord for Less

### impl Ord for UTerm

### impl Ord for PhantomPinned

### impl Ord for Alignment

### impl Ord for String

### impl Ord for Duration

### impl Ord for BigEndian

### impl Ord for H128

### impl Ord for H160

### impl Ord for H256

### impl Ord for H384

### impl Ord for H512

### impl Ord for H768

### impl Ord for LittleEndian

### impl Ord for MetaForm

### impl Ord for NonZeroU256

### impl Ord for PortableForm

### impl Ord for TypeDefPrimitive

### impl Ord for U128

### impl Ord for U256

### impl Ord for U512

### impl<'a> Ord for Location<'a>

### impl<'a, T> Ord for Symbol<'a, T>where
T: Ord + 'a,

### impl<A> Ord for &A

### impl<A> Ord for &mut A

### impl<B> Ord for Cow<'_, B>

### impl<Dyn> Ord for DynMetadata<Dyn>where
Dyn: ?Sized,

### impl<F> Ord for Fwhere
F: FnPtr,

### impl<K, V, A> Ord for BTreeMap<K, V, A>

### impl<Ptr> Ord for Pin<Ptr>

### impl<T> Ord for Option<T>where
T: Ord,

### impl<T> Ord for Poll<T>where
T: Ord,

### impl<T> Ord for *const Twhere
T: ?Sized,

### impl<T> Ord for *mut Twhere
T: ?Sized,

### impl<T> Ord for [T]where
T: Ord,

Implements comparison of slices lexicographically.

### impl<T> Ord for (T₁, T₂, …, Tₙ)

This trait is implemented for tuples up to twelve items long.

### impl<T> Ord for Cell<T>

### impl<T> Ord for RefCell<T>

### impl<T> Ord for Reverse<T>where
T: Ord,

### impl<T> Ord for CapacityError<T>where
T: Ord,

### impl<T> Ord for PhantomData<T>where
T: ?Sized,

### impl<T> Ord for ManuallyDrop<T>

### impl<T> Ord for NonZero<T>where
T: ZeroablePrimitive + Ord,

### impl<T> Ord for Saturating<T>where
T: Ord,

### impl<T> Ord for Wrapping<T>where
T: Ord,

### impl<T> Ord for NonNull<T>where
T: ?Sized,

### impl<T> Ord for Compact<T>where
T: Ord,

### impl<T> Ord for Field<T>

### impl<T> Ord for Path<T>

### impl<T> Ord for Type<T>

### impl<T> Ord for TypeDef<T>where
T: Ord + Form,

### impl<T> Ord for TypeDefArray<T>

### impl<T> Ord for TypeDefBitSequence<T>

### impl<T> Ord for TypeDefCompact<T>

### impl<T> Ord for TypeDefComposite<T>where
T: Ord + Form,

### impl<T> Ord for TypeDefSequence<T>

### impl<T> Ord for TypeDefTuple<T>

### impl<T> Ord for TypeDefVariant<T>where
T: Ord + Form,

### impl<T> Ord for TypeParameter<T>

### impl<T> Ord for Unalign<T>where
T: Unaligned + Ord,

### impl<T> Ord for UntrackedSymbol<T>where
T: Ord,

### impl<T> Ord for Variant<T>

### impl<T, A> Ord for BTreeSet<T, A>

### impl<T, A> Ord for LinkedList<T, A>

### impl<T, A> Ord for VecDeque<T, A>

### impl<T, A> Ord for Arc<T, A>

### impl<T, A> Ord for Rc<T, A>

### impl<T, A> Ord for gstd::prelude::Box<T, A>

### impl<T, A> Ord for gstd::prelude::Vec<T, A>

Implements ordering of vectors, lexicographically.

### impl<T, A> Ord for Box<T, A>

### impl<T, A> Ord for Vec<T, A>where
T: Ord,
A: Allocator,

Implements ordering of vectors, lexicographically.

### impl<T, B> Ord for Ref<B, [T]>where
B: ByteSlice,
T: FromBytes + Ord,

### impl<T, B> Ord for Ref<B, T>where
B: ByteSlice,
T: FromBytes + Ord,

### impl<T, E> Ord for Result<T, E>

### impl<T, N> Ord for GenericArray<T, N>where
T: Ord,
N: ArrayLength<T>,

### impl<T, const CAP: usize> Ord for ArrayVec<T, CAP>where
T: Ord,

### impl<T, const N: usize> Ord for [T; N]where
T: Ord,

Implements comparison of arrays lexicographically.