array - Rust
Description: API documentation for the Rust `array` primitive in crate `std`.
Keywords: rust, rustlang, rust-lang, array

# 1.0.0[−]Primitive Type array

A fixed-size array, denoted `[T; N]`, for the element type, `T`, and the non-negative compile-time constant size, `N`.

There are two syntactic forms for creating an array:

- A list with each element, i.e., `[x, y, z]`.
- A repeat expression `[x; N]`, which produces an array with `N` copies of `x`. The type of `x` must be `Copy`.

Arrays of any size implement the following traits if the element type allows it:

- `Debug`
- `IntoIterator` (implemented for `&[T; N]` and `&mut [T; N]`)
- `PartialEq`, `PartialOrd`, `Eq`, `Ord`
- `Hash`
- `AsRef`, `AsMut`
- `Borrow`, `BorrowMut`

Arrays of sizes from 0 to 32 (inclusive) implement `Default` trait if the element type allows it. As a stopgap, trait implementations are statically generated up to size 32.

Arrays of any size are `Copy` if the element type is `Copy` and `Clone` if the element type is `Clone`. This works because `Copy` and `Clone` traits are specially known to the compiler.

Arrays coerce to slices (`[T]`), so a slice method may be called on an array. Indeed, this provides most of the API for working with arrays. Slices have a dynamic size and do not coerce to arrays.

You can move elements out of an array with a slice pattern. If you want one element, see `mem::replace`.

# Examples

    let mut array: [i32; 3] = [0; 3];

    array[1] = 1;
    array[2] = 2;

    assert_eq!([1, 2], &array[1..]);

    // This loop prints: 0 1 2
    for x in &array {
        print!("{} ", x);
    }

Run

An array itself is not iterable:

ⓘThis example deliberately fails to compile

    let array: [i32; 3] = [0; 3];

    for x in array { }
    // error: the trait bound `[i32; 3]: std::iter::Iterator` is not satisfied

Run

The solution is to coerce the array to a slice by calling a slice method:

    for x in array.iter() { }

Run

You can also use the array reference's `IntoIterator` implementation:

    for x in &array { }

Run

You can use a slice pattern to move elements out of an array:

    fn move_away(_: String) { /* Do interesting things. */ }

    let [john, roa] = ["John".to_string(), "Roa".to_string()];
    move_away(john);
    move_away(roa);

Run

## Implementations

### `impl<T, const N: usize> [T; N]`[src]

#### `pub fn map<F, U>(self, f: F) -> [U; N] where
F: FnMut(T) -> U,` [src]

🔬 This is a nightly-only experimental API. (`array_map` #75243)

Returns an array of the same size as `self`, with function `f` applied to each element in order.

# Examples

    #![feature(array_map)]
    let x = [1, 2, 3];
    let y = x.map(|v| v + 1);
    assert_eq!(y, [2, 3, 4]);

    let x = [1, 2, 3];
    let mut temp = 0;
    let y = x.map(|v| { temp += 1; v * temp });
    assert_eq!(y, [1, 4, 9]);

    let x = ["Ferris", "Bueller's", "Day", "Off"];
    let y = x.map(|v| v.len());
    assert_eq!(y, [6, 9, 3, 3]);

Run

## Trait Implementations

### `impl<T, const N: usize> AsMut<[T]> for [T; N]`[src]

#### `fn as_mut(&mut self) -> &mut [T]ⓘ

### Notable traits for &'_ [u8]

`impl<'_> Read for &'_ [u8]impl<'_> Write for &'_ mut [u8]`
`[src]

Performs the conversion.

### `impl<T, const N: usize> AsRef<[T]> for [T; N]`[src]

#### `fn as_ref(&self) -> &[T]ⓘ

### Notable traits for &'_ [u8]

`impl<'_> Read for &'_ [u8]impl<'_> Write for &'_ mut [u8]`
`[src]

Performs the conversion.

### `impl<T, const N: usize> Borrow<[T]> for [T; N]`1.4.0[src]

#### `fn borrow(&self) -> &[T]ⓘ

### Notable traits for &'_ [u8]

`impl<'_> Read for &'_ [u8]impl<'_> Write for &'_ mut [u8]`
`[src]

Immutably borrows from an owned value. Read more

### `impl<T, const N: usize> BorrowMut<[T]> for [T; N]`1.4.0[src]

#### `fn borrow_mut(&mut self) -> &mut [T]ⓘ

### Notable traits for &'_ [u8]

`impl<'_> Read for &'_ [u8]impl<'_> Write for &'_ mut [u8]`
`[src]

Mutably borrows from an owned value. Read more

### `impl<T, const N: usize> Debug for [T; N] where
T: Debug,` [src]

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

Formats the value using the given formatter. Read more

### `impl<T> Default for [T; 18] where
T: Default,` 1.4.0[src]

#### `fn default() -> [T; 18]`[src]

Returns the "default value" for a type. Read more

### `impl<T> Default for [T; 21] where
T: Default,` 1.4.0[src]

#### `fn default() -> [T; 21]`[src]

Returns the "default value" for a type. Read more

### `impl<T> Default for [T; 13] where
T: Default,` 1.4.0[src]

#### `fn default() -> [T; 13]`[src]

Returns the "default value" for a type. Read more

### `impl<T> Default for [T; 27] where
T: Default,` 1.4.0[src]

#### `fn default() -> [T; 27]`[src]

Returns the "default value" for a type. Read more

### `impl<T> Default for [T; 25] where
T: Default,` 1.4.0[src]

#### `fn default() -> [T; 25]`[src]

Returns the "default value" for a type. Read more

### `impl<T> Default for [T; 2] where
T: Default,` 1.4.0[src]

#### `fn default() -> [T; 2]`[src]

Returns the "default value" for a type. Read more

### `impl<T> Default for [T; 16] where
T: Default,` 1.4.0[src]

#### `fn default() -> [T; 16]`[src]

Returns the "default value" for a type. Read more

### `impl<T> Default for [T; 1] where
T: Default,` 1.4.0[src]

#### `fn default() -> [T; 1]`[src]

Returns the "default value" for a type. Read more

### `impl<T> Default for [T; 7] where
T: Default,` 1.4.0[src]

#### `fn default() -> [T; 7]`[src]

Returns the "default value" for a type. Read more

### `impl<T> Default for [T; 3] where
T: Default,` 1.4.0[src]

#### `fn default() -> [T; 3]`[src]

Returns the "default value" for a type. Read more

### `impl<T> Default for [T; 23] where
T: Default,` 1.4.0[src]

#### `fn default() -> [T; 23]`[src]

Returns the "default value" for a type. Read more

### `impl<T> Default for [T; 20] where
T: Default,` 1.4.0[src]

#### `fn default() -> [T; 20]`[src]

Returns the "default value" for a type. Read more

### `impl<T> Default for [T; 32] where
T: Default,` 1.4.0[src]

#### `fn default() -> [T; 32]`[src]

Returns the "default value" for a type. Read more

### `impl<T> Default for [T; 5] where
T: Default,` 1.4.0[src]

#### `fn default() -> [T; 5]`[src]

Returns the "default value" for a type. Read more

### `impl<T> Default for [T; 8] where
T: Default,` 1.4.0[src]

#### `fn default() -> [T; 8]`[src]

Returns the "default value" for a type. Read more

### `impl<T> Default for [T; 14] where
T: Default,` 1.4.0[src]

#### `fn default() -> [T; 14]`[src]

Returns the "default value" for a type. Read more

### `impl<T> Default for [T; 26] where
T: Default,` 1.4.0[src]

#### `fn default() -> [T; 26]`[src]

Returns the "default value" for a type. Read more

### `impl<T> Default for [T; 9] where
T: Default,` 1.4.0[src]

#### `fn default() -> [T; 9]`[src]

Returns the "default value" for a type. Read more

### `impl<T> Default for [T; 28] where
T: Default,` 1.4.0[src]

#### `fn default() -> [T; 28]`[src]

Returns the "default value" for a type. Read more

### `impl<T> Default for [T; 17] where
T: Default,` 1.4.0[src]

#### `fn default() -> [T; 17]`[src]

Returns the "default value" for a type. Read more

### `impl<T> Default for [T; 31] where
T: Default,` 1.4.0[src]

#### `fn default() -> [T; 31]`[src]

Returns the "default value" for a type. Read more

### `impl<T> Default for [T; 0]`1.4.0[src]

#### `fn default() -> [T; 0]`[src]

Returns the "default value" for a type. Read more

### `impl<T> Default for [T; 6] where
T: Default,` 1.4.0[src]

#### `fn default() -> [T; 6]`[src]

Returns the "default value" for a type. Read more

### `impl<T> Default for [T; 30] where
T: Default,` 1.4.0[src]

#### `fn default() -> [T; 30]`[src]

Returns the "default value" for a type. Read more

### `impl<T> Default for [T; 29] where
T: Default,` 1.4.0[src]

#### `fn default() -> [T; 29]`[src]

Returns the "default value" for a type. Read more

### `impl<T> Default for [T; 15] where
T: Default,` 1.4.0[src]

#### `fn default() -> [T; 15]`[src]

Returns the "default value" for a type. Read more

### `impl<T> Default for [T; 11] where
T: Default,` 1.4.0[src]

#### `fn default() -> [T; 11]`[src]

Returns the "default value" for a type. Read more

### `impl<T> Default for [T; 10] where
T: Default,` 1.4.0[src]

#### `fn default() -> [T; 10]`[src]

Returns the "default value" for a type. Read more

### `impl<T> Default for [T; 4] where
T: Default,` 1.4.0[src]

#### `fn default() -> [T; 4]`[src]

Returns the "default value" for a type. Read more

### `impl<T> Default for [T; 12] where
T: Default,` 1.4.0[src]

#### `fn default() -> [T; 12]`[src]

Returns the "default value" for a type. Read more

### `impl<T> Default for [T; 22] where
T: Default,` 1.4.0[src]

#### `fn default() -> [T; 22]`[src]

Returns the "default value" for a type. Read more

### `impl<T> Default for [T; 19] where
T: Default,` 1.4.0[src]

#### `fn default() -> [T; 19]`[src]

Returns the "default value" for a type. Read more

### `impl<T> Default for [T; 24] where
T: Default,` 1.4.0[src]

#### `fn default() -> [T; 24]`[src]

Returns the "default value" for a type. Read more

### `impl<T, const N: usize> Eq for [T; N] where
T: Eq,` [src]

### `impl<T, const N: usize> Hash for [T; N] where
T: Hash,` [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<'a, T, const N: usize> IntoIterator for &'a mut [T; N]`[src]

#### `type Item = &'a mut T`

The type of the elements being iterated over.

#### `type IntoIter = IterMut<'a, T>`

Which kind of iterator are we turning this into?

#### `fn into_iter(self) -> IterMut<'a, T>ⓘ

### Notable traits for IterMut<'a, T>

`impl<'a, T> Iterator for IterMut<'a, T> type Item = &'a mut T;`
`[src]

Creates an iterator from a value. Read more

### `impl<'a, T, const N: usize> IntoIterator for &'a [T; N]`[src]

#### `type Item = &'a T`

The type of the elements being iterated over.

#### `type IntoIter = Iter<'a, T>`

Which kind of iterator are we turning this into?

#### `fn into_iter(self) -> Iter<'a, T>ⓘ

### Notable traits for Iter<'a, T>

`impl<'a, T> Iterator for Iter<'a, T> type Item = &'a T;`
`[src]

Creates an iterator from a value. Read more

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

Implements comparison of arrays lexicographically.

#### `fn cmp(&self, other: &[T; N]) -> Ordering`[src]

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

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

Compares and returns the maximum of two values. Read more

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

Compares and returns the minimum of two values. Read more

#### `#[must_use]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<'b, A, B, const N: usize> PartialEq<&'b [B]> for [A; N] where
A: PartialEq<B>,` [src]

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

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

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

This method tests for `!=`.

### `impl<'b, A, B, const N: usize> PartialEq<&'b mut [B]> for [A; N] where
A: PartialEq<B>,` [src]

#### `fn eq(&self, other: &&'b mut [B]) -> bool`[src]

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

#### `fn ne(&self, other: &&'b mut [B]) -> bool`[src]

This method tests for `!=`.

### `impl<A, B, const N: usize> PartialEq<[B; N]> for [A; N] where
A: PartialEq<B>,` [src]

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

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

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

This method tests for `!=`.

### `impl<A, B, const N: usize> PartialEq<[B]> for [A; N] where
A: PartialEq<B>,` [src]

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

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

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

This method tests for `!=`.

### `impl<T, const N: usize> PartialOrd<[T; N]> for [T; N] where
T: PartialOrd<T>,` [src]

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

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

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

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

#### `fn le(&self, other: &[T; N]) -> bool`[src]

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

#### `fn ge(&self, other: &[T; N]) -> bool`[src]

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

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

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

### `impl<'_, T, const N: usize> TryFrom<&'_ [T]> for [T; N] where
T: Copy,` 1.34.0[src]

#### `type Error = TryFromSliceError`

The type returned in the event of a conversion error.

#### `fn try_from(slice: &[T]) -> Result<[T; N], TryFromSliceError>`[src]

Performs the conversion.

### `impl<'a, T, const N: usize> TryFrom<&'a [T]> for &'a [T; N]`1.34.0[src]

#### `type Error = TryFromSliceError`

The type returned in the event of a conversion error.

#### `fn try_from(slice: &[T]) -> Result<&[T; N], TryFromSliceError>`[src]

Performs the conversion.

### `impl<'a, T, const N: usize> TryFrom<&'a mut [T]> for &'a mut [T; N]`1.34.0[src]

#### `type Error = TryFromSliceError`

The type returned in the event of a conversion error.

#### `fn try_from(slice: &mut [T]) -> Result<&mut [T; N], TryFromSliceError>`[src]

Performs the conversion.

## Auto Trait Implementations

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

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

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

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

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

## Blanket Implementations

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

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

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

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

#### `fn borrow(&self) -> &Tⓘ

### Notable traits for &'_ mut I

`impl<'_, I> Iterator for &'_ mut I where
I: Iterator + ?Sized, type Item = <I as Iterator>::Item;impl<'_, F> Future for &'_ mut F where
F: Unpin + Future + ?Sized, type Output = <F as Future>::Output;impl<R: Read + ?Sized, '_> Read for &'_ mut Rimpl<W: Write + ?Sized, '_> Write for &'_ mut W`
`[src]

Immutably borrows from an owned value. Read more

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

#### `fn borrow_mut(&mut self) -> &mut Tⓘ

### Notable traits for &'_ mut I

`impl<'_, I> Iterator for &'_ mut I where
I: Iterator + ?Sized, type Item = <I as Iterator>::Item;impl<'_, F> Future for &'_ mut F where
F: Unpin + Future + ?Sized, type Output = <F as Future>::Output;impl<R: Read + ?Sized, '_> Read for &'_ mut Rimpl<W: Write + ?Sized, '_> Write for &'_ mut W`
`[src]

Mutably borrows from an owned value. Read more

### `impl<T, A> FixedSizeArray<T> for A where
A: Unsize<[T]>,` [src]

#### `fn as_slice(&self) -> &[T]ⓘ

### Notable traits for &'_ [u8]

`impl<'_> Read for &'_ [u8]impl<'_> Write for &'_ mut [u8]`
`[src]

🔬 This is a nightly-only experimental API. (`fixed_size_array` #27778)

Converts the array to immutable slice

#### `fn as_mut_slice(&mut self) -> &mut [T]ⓘ

### Notable traits for &'_ [u8]

`impl<'_> Read for &'_ [u8]impl<'_> Write for &'_ mut [u8]`
`[src]

🔬 This is a nightly-only experimental API. (`fixed_size_array` #27778)

Converts the array to mutable slice

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

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

Performs the conversion.

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

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

Performs the conversion.

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

#### `type Owned = T`

The resulting type after obtaining ownership.

#### `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)

recently added

Uses borrowed data to replace owned data, usually by cloning. Read more

### `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.

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

Performs the conversion.

### `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.

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

Performs the conversion.