/Rust

# Primitive Type slice

A dynamically-sized view into a contiguous sequence, `[T]`.

See also the `std::slice` module.

Slices are a view into a block of memory represented as a pointer and a length.

```// slicing a Vec
let vec = vec![1, 2, 3];
let int_slice = &vec[..];
// coercing an array to a slice
let str_slice: &[&str] = &["one", "two", "three"];```

Slices are either mutable or shared. The shared slice type is `&[T]`, while the mutable slice type is `&mut [T]`, where `T` represents the element type. For example, you can mutate the block of memory that a mutable slice points to:

```let mut x = [1, 2, 3];
let x = &mut x[..]; // Take a full slice of `x`.
x = 7;
assert_eq!(x, &[1, 7, 3]);```

## Methods

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

#### `pub fn len(&self) -> usize`[src]

Returns the number of elements in the slice.

## Examples

```let a = [1, 2, 3];
assert_eq!(a.len(), 3);```

#### `pub fn is_empty(&self) -> bool`[src]

Returns `true` if the slice has a length of 0.

## Examples

```let a = [1, 2, 3];
assert!(!a.is_empty());```

#### `pub fn first(&self) -> Option<&T>`[src]

Returns the first element of the slice, or `None` if it is empty.

## Examples

```let v = [10, 40, 30];
assert_eq!(Some(&10), v.first());

let w: &[i32] = &[];
assert_eq!(None, w.first());```

#### `pub fn first_mut(&mut self) -> Option<&mut T>`[src]

Returns a mutable pointer to the first element of the slice, or `None` if it is empty.

## Examples

```let x = &mut [0, 1, 2];

if let Some(first) = x.first_mut() {
*first = 5;
}
assert_eq!(x, &[5, 1, 2]);```

#### `pub fn split_first(&self) -> Option<(&T, &[T])>`[src]1.5.0

Returns the first and all the rest of the elements of the slice, or `None` if it is empty.

## Examples

```let x = &[0, 1, 2];

if let Some((first, elements)) = x.split_first() {
assert_eq!(first, &0);
assert_eq!(elements, &[1, 2]);
}```

#### `pub fn split_first_mut(&mut self) -> Option<(&mut T, &mut [T])>`[src]1.5.0

Returns the first and all the rest of the elements of the slice, or `None` if it is empty.

## Examples

```let x = &mut [0, 1, 2];

if let Some((first, elements)) = x.split_first_mut() {
*first = 3;
elements = 4;
elements = 5;
}
assert_eq!(x, &[3, 4, 5]);```

#### `pub fn split_last(&self) -> Option<(&T, &[T])>`[src]1.5.0

Returns the last and all the rest of the elements of the slice, or `None` if it is empty.

## Examples

```let x = &[0, 1, 2];

if let Some((last, elements)) = x.split_last() {
assert_eq!(last, &2);
assert_eq!(elements, &[0, 1]);
}```

#### `pub fn split_last_mut(&mut self) -> Option<(&mut T, &mut [T])>`[src]1.5.0

Returns the last and all the rest of the elements of the slice, or `None` if it is empty.

## Examples

```let x = &mut [0, 1, 2];

if let Some((last, elements)) = x.split_last_mut() {
*last = 3;
elements = 4;
elements = 5;
}
assert_eq!(x, &[4, 5, 3]);```

#### `pub fn last(&self) -> Option<&T>`[src]

Returns the last element of the slice, or `None` if it is empty.

## Examples

```let v = [10, 40, 30];
assert_eq!(Some(&30), v.last());

let w: &[i32] = &[];
assert_eq!(None, w.last());```

#### `pub fn last_mut(&mut self) -> Option<&mut T>`[src]

Returns a mutable pointer to the last item in the slice.

## Examples

```let x = &mut [0, 1, 2];

if let Some(last) = x.last_mut() {
*last = 10;
}
assert_eq!(x, &[0, 1, 10]);```

#### `pub fn get<I>(&self, index: I) -> Option<&<I as SliceIndex<[T]>>::Output> where    I: SliceIndex<[T]>, `[src]

Returns a reference to an element or subslice depending on the type of index.

• If given a position, returns a reference to the element at that position or `None` if out of bounds.
• If given a range, returns the subslice corresponding to that range, or `None` if out of bounds.

## Examples

```let v = [10, 40, 30];
assert_eq!(Some(&40), v.get(1));
assert_eq!(Some(&[10, 40][..]), v.get(0..2));
assert_eq!(None, v.get(3));
assert_eq!(None, v.get(0..4));```

#### `pub fn get_mut<I>(    &mut self,     index: I) -> Option<&mut <I as SliceIndex<[T]>>::Output> where    I: SliceIndex<[T]>, `[src]

Returns a mutable reference to an element or subslice depending on the type of index (see `get`) or `None` if the index is out of bounds.

## Examples

```let x = &mut [0, 1, 2];

if let Some(elem) = x.get_mut(1) {
*elem = 42;
}
assert_eq!(x, &[0, 42, 2]);```

#### `pub unsafe fn get_unchecked<I>(    &self,     index: I) -> &<I as SliceIndex<[T]>>::Output where    I: SliceIndex<[T]>, `[src]

Returns a reference to an element or subslice, without doing bounds checking.

This is generally not recommended, use with caution! For a safe alternative see `get`.

## Examples

```let x = &[1, 2, 4];

unsafe {
assert_eq!(x.get_unchecked(1), &2);
}```

#### `pub unsafe fn get_unchecked_mut<I>(    &mut self,     index: I) -> &mut <I as SliceIndex<[T]>>::Output where    I: SliceIndex<[T]>, `[src]

Returns a mutable reference to an element or subslice, without doing bounds checking.

This is generally not recommended, use with caution! For a safe alternative see `get_mut`.

## Examples

```let x = &mut [1, 2, 4];

unsafe {
let elem = x.get_unchecked_mut(1);
*elem = 13;
}
assert_eq!(x, &[1, 13, 4]);```

#### `pub const fn as_ptr(&self) -> *const T`[src]

Returns a raw pointer to the slice's buffer.

The caller must ensure that the slice outlives the pointer this function returns, or else it will end up pointing to garbage.

The caller must also ensure that the memory the pointer (non-transitively) points to is never written to (except inside an `UnsafeCell`) using this pointer or any pointer derived from it. If you need to mutate the contents of the slice, use `as_mut_ptr`.

Modifying the container referenced by this slice may cause its buffer to be reallocated, which would also make any pointers to it invalid.

## Examples

```let x = &[1, 2, 4];
let x_ptr = x.as_ptr();

unsafe {
for i in 0..x.len() {
}
}```

#### `pub fn as_mut_ptr(&mut self) -> *mut T`[src]

Returns an unsafe mutable pointer to the slice's buffer.

The caller must ensure that the slice outlives the pointer this function returns, or else it will end up pointing to garbage.

Modifying the container referenced by this slice may cause its buffer to be reallocated, which would also make any pointers to it invalid.

## Examples

```let x = &mut [1, 2, 4];
let x_ptr = x.as_mut_ptr();

unsafe {
for i in 0..x.len() {
}
}
assert_eq!(x, &[3, 4, 6]);```

#### `pub fn swap(&mut self, a: usize, b: usize)`[src]

Swaps two elements in the slice.

## Arguments

• a - The index of the first element
• b - The index of the second element

## Panics

Panics if `a` or `b` are out of bounds.

## Examples

```let mut v = ["a", "b", "c", "d"];
v.swap(1, 3);
assert!(v == ["a", "d", "c", "b"]);```

#### `pub fn reverse(&mut self)`[src]

Reverses the order of elements in the slice, in place.

## Examples

```let mut v = [1, 2, 3];
v.reverse();
assert!(v == [3, 2, 1]);```

#### `pub fn iter(&self) -> Iter<T>`[src]

ⓘImportant traits for Iter<'a, T>
```impl<'a, T> Iterator for Iter<'a, T>
type Item = &'a T;
```

Returns an iterator over the slice.

## Examples

```let x = &[1, 2, 4];
let mut iterator = x.iter();

assert_eq!(iterator.next(), Some(&1));
assert_eq!(iterator.next(), Some(&2));
assert_eq!(iterator.next(), Some(&4));
assert_eq!(iterator.next(), None);```

#### `pub fn iter_mut(&mut self) -> IterMut<T>`[src]

ⓘImportant traits for IterMut<'a, T>
```impl<'a, T> Iterator for IterMut<'a, T>
type Item = &'a mut T;
```

Returns an iterator that allows modifying each value.

## Examples

```let x = &mut [1, 2, 4];
for elem in x.iter_mut() {
*elem += 2;
}
assert_eq!(x, &[3, 4, 6]);```

#### `pub fn windows(&self, size: usize) -> Windows<T>`[src]

ⓘImportant traits for Windows<'a, T>
```impl<'a, T> Iterator for Windows<'a, T>
type Item = &'a [T];
```

Returns an iterator over all contiguous windows of length `size`. The windows overlap. If the slice is shorter than `size`, the iterator returns no values.

## Panics

Panics if `size` is 0.

## Examples

```let slice = ['r', 'u', 's', 't'];
let mut iter = slice.windows(2);
assert_eq!(iter.next().unwrap(), &['r', 'u']);
assert_eq!(iter.next().unwrap(), &['u', 's']);
assert_eq!(iter.next().unwrap(), &['s', 't']);
assert!(iter.next().is_none());```

If the slice is shorter than `size`:

```let slice = ['f', 'o', 'o'];
let mut iter = slice.windows(4);
assert!(iter.next().is_none());```

#### `pub fn chunks(&self, chunk_size: usize) -> Chunks<T>`[src]

ⓘImportant traits for Chunks<'a, T>
```impl<'a, T> Iterator for Chunks<'a, T>
type Item = &'a [T];
```

Returns an iterator over `chunk_size` elements of the slice at a time, starting at the beginning of the slice.

The chunks are slices and do not overlap. If `chunk_size` does not divide the length of the slice, then the last chunk will not have length `chunk_size`.

See `chunks_exact` for a variant of this iterator that returns chunks of always exactly `chunk_size` elements, and `rchunks` for the same iterator but starting at the end of the slice of the slice.

## Panics

Panics if `chunk_size` is 0.

## Examples

```let slice = ['l', 'o', 'r', 'e', 'm'];
let mut iter = slice.chunks(2);
assert_eq!(iter.next().unwrap(), &['l', 'o']);
assert_eq!(iter.next().unwrap(), &['r', 'e']);
assert_eq!(iter.next().unwrap(), &['m']);
assert!(iter.next().is_none());```

#### `pub fn chunks_mut(&mut self, chunk_size: usize) -> ChunksMut<T>`[src]

ⓘImportant traits for ChunksMut<'a, T>
```impl<'a, T> Iterator for ChunksMut<'a, T>
type Item = &'a mut [T];
```

Returns an iterator over `chunk_size` elements of the slice at a time, starting at the beginning of the slice.

The chunks are mutable slices, and do not overlap. If `chunk_size` does not divide the length of the slice, then the last chunk will not have length `chunk_size`.

See `chunks_exact_mut` for a variant of this iterator that returns chunks of always exactly `chunk_size` elements, and `rchunks_mut` for the same iterator but starting at the end of the slice of the slice.

## Panics

Panics if `chunk_size` is 0.

## Examples

```let v = &mut [0, 0, 0, 0, 0];
let mut count = 1;

for chunk in v.chunks_mut(2) {
for elem in chunk.iter_mut() {
*elem += count;
}
count += 1;
}
assert_eq!(v, &[1, 1, 2, 2, 3]);```

#### `pub fn chunks_exact(&self, chunk_size: usize) -> ChunksExact<T>`[src]1.31.0

ⓘImportant traits for ChunksExact<'a, T>
```impl<'a, T> Iterator for ChunksExact<'a, T>
type Item = &'a [T];
```

Returns an iterator over `chunk_size` elements of the slice at a time, starting at the beginning of the slice.

The chunks are slices and do not overlap. If `chunk_size` does not divide the length of the slice, then the last up to `chunk_size-1` elements will be omitted and can be retrieved from the `remainder` function of the iterator.

Due to each chunk having exactly `chunk_size` elements, the compiler can often optimize the resulting code better than in the case of `chunks`.

See `chunks` for a variant of this iterator that also returns the remainder as a smaller chunk, and `rchunks_exact` for the same iterator but starting at the end of the slice.

## Panics

Panics if `chunk_size` is 0.

## Examples

```let slice = ['l', 'o', 'r', 'e', 'm'];
let mut iter = slice.chunks_exact(2);
assert_eq!(iter.next().unwrap(), &['l', 'o']);
assert_eq!(iter.next().unwrap(), &['r', 'e']);
assert!(iter.next().is_none());
assert_eq!(iter.remainder(), &['m']);```

#### `pub fn chunks_exact_mut(&mut self, chunk_size: usize) -> ChunksExactMut<T>`[src]1.31.0

ⓘImportant traits for ChunksExactMut<'a, T>
```impl<'a, T> Iterator for ChunksExactMut<'a, T>
type Item = &'a mut [T];
```

Returns an iterator over `chunk_size` elements of the slice at a time, starting at the beginning of the slice.

The chunks are mutable slices, and do not overlap. If `chunk_size` does not divide the length of the slice, then the last up to `chunk_size-1` elements will be omitted and can be retrieved from the `into_remainder` function of the iterator.

Due to each chunk having exactly `chunk_size` elements, the compiler can often optimize the resulting code better than in the case of `chunks_mut`.

See `chunks_mut` for a variant of this iterator that also returns the remainder as a smaller chunk, and `rchunks_exact_mut` for the same iterator but starting at the end of the slice of the slice.

## Panics

Panics if `chunk_size` is 0.

## Examples

```let v = &mut [0, 0, 0, 0, 0];
let mut count = 1;

for chunk in v.chunks_exact_mut(2) {
for elem in chunk.iter_mut() {
*elem += count;
}
count += 1;
}
assert_eq!(v, &[1, 1, 2, 2, 0]);```

#### `pub fn rchunks(&self, chunk_size: usize) -> RChunks<T>`[src]1.31.0

ⓘImportant traits for RChunks<'a, T>
```impl<'a, T> Iterator for RChunks<'a, T>
type Item = &'a [T];
```

Returns an iterator over `chunk_size` elements of the slice at a time, starting at the end of the slice.

The chunks are slices and do not overlap. If `chunk_size` does not divide the length of the slice, then the last chunk will not have length `chunk_size`.

See `rchunks_exact` for a variant of this iterator that returns chunks of always exactly `chunk_size` elements, and `chunks` for the same iterator but starting at the beginning of the slice.

## Panics

Panics if `chunk_size` is 0.

## Examples

```let slice = ['l', 'o', 'r', 'e', 'm'];
let mut iter = slice.rchunks(2);
assert_eq!(iter.next().unwrap(), &['e', 'm']);
assert_eq!(iter.next().unwrap(), &['o', 'r']);
assert_eq!(iter.next().unwrap(), &['l']);
assert!(iter.next().is_none());```

#### `pub fn rchunks_mut(&mut self, chunk_size: usize) -> RChunksMut<T>`[src]1.31.0

ⓘImportant traits for RChunksMut<'a, T>
```impl<'a, T> Iterator for RChunksMut<'a, T>
type Item = &'a mut [T];
```

Returns an iterator over `chunk_size` elements of the slice at a time, starting at the end of the slice.

The chunks are mutable slices, and do not overlap. If `chunk_size` does not divide the length of the slice, then the last chunk will not have length `chunk_size`.

See `rchunks_exact_mut` for a variant of this iterator that returns chunks of always exactly `chunk_size` elements, and `chunks_mut` for the same iterator but starting at the beginning of the slice.

## Panics

Panics if `chunk_size` is 0.

## Examples

```let v = &mut [0, 0, 0, 0, 0];
let mut count = 1;

for chunk in v.rchunks_mut(2) {
for elem in chunk.iter_mut() {
*elem += count;
}
count += 1;
}
assert_eq!(v, &[3, 2, 2, 1, 1]);```

#### `pub fn rchunks_exact(&self, chunk_size: usize) -> RChunksExact<T>`[src]1.31.0

ⓘImportant traits for RChunksExact<'a, T>
```impl<'a, T> Iterator for RChunksExact<'a, T>
type Item = &'a [T];
```

Returns an iterator over `chunk_size` elements of the slice at a time, starting at the end of the slice.

The chunks are slices and do not overlap. If `chunk_size` does not divide the length of the slice, then the last up to `chunk_size-1` elements will be omitted and can be retrieved from the `remainder` function of the iterator.

Due to each chunk having exactly `chunk_size` elements, the compiler can often optimize the resulting code better than in the case of `chunks`.

See `rchunks` for a variant of this iterator that also returns the remainder as a smaller chunk, and `chunks_exact` for the same iterator but starting at the beginning of the slice.

## Panics

Panics if `chunk_size` is 0.

## Examples

```let slice = ['l', 'o', 'r', 'e', 'm'];
let mut iter = slice.rchunks_exact(2);
assert_eq!(iter.next().unwrap(), &['e', 'm']);
assert_eq!(iter.next().unwrap(), &['o', 'r']);
assert!(iter.next().is_none());
assert_eq!(iter.remainder(), &['l']);```

#### `pub fn rchunks_exact_mut(&mut self, chunk_size: usize) -> RChunksExactMut<T>`[src]1.31.0

ⓘImportant traits for RChunksExactMut<'a, T>
```impl<'a, T> Iterator for RChunksExactMut<'a, T>
type Item = &'a mut [T];
```

Returns an iterator over `chunk_size` elements of the slice at a time, starting at the end of the slice.

The chunks are mutable slices, and do not overlap. If `chunk_size` does not divide the length of the slice, then the last up to `chunk_size-1` elements will be omitted and can be retrieved from the `into_remainder` function of the iterator.

Due to each chunk having exactly `chunk_size` elements, the compiler can often optimize the resulting code better than in the case of `chunks_mut`.

See `rchunks_mut` for a variant of this iterator that also returns the remainder as a smaller chunk, and `chunks_exact_mut` for the same iterator but starting at the beginning of the slice.

## Panics

Panics if `chunk_size` is 0.

## Examples

```let v = &mut [0, 0, 0, 0, 0];
let mut count = 1;

for chunk in v.rchunks_exact_mut(2) {
for elem in chunk.iter_mut() {
*elem += count;
}
count += 1;
}
assert_eq!(v, &[0, 2, 2, 1, 1]);```

#### `pub fn split_at(&self, mid: usize) -> (&[T], &[T])`[src]

Divides one slice into two at an index.

The first will contain all indices from `[0, mid)` (excluding the index `mid` itself) and the second will contain all indices from `[mid, len)` (excluding the index `len` itself).

## Panics

Panics if `mid > len`.

## Examples

```let v = [1, 2, 3, 4, 5, 6];

{
let (left, right) = v.split_at(0);
assert!(left == []);
assert!(right == [1, 2, 3, 4, 5, 6]);
}

{
let (left, right) = v.split_at(2);
assert!(left == [1, 2]);
assert!(right == [3, 4, 5, 6]);
}

{
let (left, right) = v.split_at(6);
assert!(left == [1, 2, 3, 4, 5, 6]);
assert!(right == []);
}```

#### `pub fn split_at_mut(&mut self, mid: usize) -> (&mut [T], &mut [T])`[src]

Divides one mutable slice into two at an index.

The first will contain all indices from `[0, mid)` (excluding the index `mid` itself) and the second will contain all indices from `[mid, len)` (excluding the index `len` itself).

## Panics

Panics if `mid > len`.

## Examples

```let mut v = [1, 0, 3, 0, 5, 6];
// scoped to restrict the lifetime of the borrows
{
let (left, right) = v.split_at_mut(2);
assert!(left == [1, 0]);
assert!(right == [3, 0, 5, 6]);
left = 2;
right = 4;
}
assert!(v == [1, 2, 3, 4, 5, 6]);```

#### `pub fn split<F>(&self, pred: F) -> Split<T, F> where    F: FnMut(&T) -> bool, `[src]

ⓘImportant traits for Split<'a, T, P>
```impl<'a, T, P> Iterator for Split<'a, T, P> where
P: FnMut(&T) -> bool,
type Item = &'a [T];
```

Returns an iterator over subslices separated by elements that match `pred`. The matched element is not contained in the subslices.

## Examples

```let slice = [10, 40, 33, 20];
let mut iter = slice.split(|num| num % 3 == 0);

assert_eq!(iter.next().unwrap(), &[10, 40]);
assert_eq!(iter.next().unwrap(), &);
assert!(iter.next().is_none());```

If the first element is matched, an empty slice will be the first item returned by the iterator. Similarly, if the last element in the slice is matched, an empty slice will be the last item returned by the iterator:

```let slice = [10, 40, 33];
let mut iter = slice.split(|num| num % 3 == 0);

assert_eq!(iter.next().unwrap(), &[10, 40]);
assert_eq!(iter.next().unwrap(), &[]);
assert!(iter.next().is_none());```

If two matched elements are directly adjacent, an empty slice will be present between them:

```let slice = [10, 6, 33, 20];
let mut iter = slice.split(|num| num % 3 == 0);

assert_eq!(iter.next().unwrap(), &);
assert_eq!(iter.next().unwrap(), &[]);
assert_eq!(iter.next().unwrap(), &);
assert!(iter.next().is_none());```

#### `pub fn split_mut<F>(&mut self, pred: F) -> SplitMut<T, F> where    F: FnMut(&T) -> bool, `[src]

ⓘImportant traits for SplitMut<'a, T, P>
```impl<'a, T, P> Iterator for SplitMut<'a, T, P> where
P: FnMut(&T) -> bool,
type Item = &'a mut [T];
```

Returns an iterator over mutable subslices separated by elements that match `pred`. The matched element is not contained in the subslices.

## Examples

```let mut v = [10, 40, 30, 20, 60, 50];

for group in v.split_mut(|num| *num % 3 == 0) {
group = 1;
}
assert_eq!(v, [1, 40, 30, 1, 60, 1]);```

#### `pub fn rsplit<F>(&self, pred: F) -> RSplit<T, F> where    F: FnMut(&T) -> bool, `[src]1.27.0

ⓘImportant traits for RSplit<'a, T, P>
```impl<'a, T, P> Iterator for RSplit<'a, T, P> where
P: FnMut(&T) -> bool,
type Item = &'a [T];
```

Returns an iterator over subslices separated by elements that match `pred`, starting at the end of the slice and working backwards. The matched element is not contained in the subslices.

## Examples

```let slice = [11, 22, 33, 0, 44, 55];
let mut iter = slice.rsplit(|num| *num == 0);

assert_eq!(iter.next().unwrap(), &[44, 55]);
assert_eq!(iter.next().unwrap(), &[11, 22, 33]);
assert_eq!(iter.next(), None);```

As with `split()`, if the first or last element is matched, an empty slice will be the first (or last) item returned by the iterator.

```let v = &[0, 1, 1, 2, 3, 5, 8];
let mut it = v.rsplit(|n| *n % 2 == 0);
assert_eq!(it.next().unwrap(), &[]);
assert_eq!(it.next().unwrap(), &[3, 5]);
assert_eq!(it.next().unwrap(), &[1, 1]);
assert_eq!(it.next().unwrap(), &[]);
assert_eq!(it.next(), None);```

#### `pub fn rsplit_mut<F>(&mut self, pred: F) -> RSplitMut<T, F> where    F: FnMut(&T) -> bool, `[src]1.27.0

ⓘImportant traits for RSplitMut<'a, T, P>
```impl<'a, T, P> Iterator for RSplitMut<'a, T, P> where
P: FnMut(&T) -> bool,
type Item = &'a mut [T];
```

Returns an iterator over mutable subslices separated by elements that match `pred`, starting at the end of the slice and working backwards. The matched element is not contained in the subslices.

## Examples

```let mut v = [100, 400, 300, 200, 600, 500];

let mut count = 0;
for group in v.rsplit_mut(|num| *num % 3 == 0) {
count += 1;
group = count;
}
assert_eq!(v, [3, 400, 300, 2, 600, 1]);```

#### `pub fn splitn<F>(&self, n: usize, pred: F) -> SplitN<T, F> where    F: FnMut(&T) -> bool, `[src]

ⓘImportant traits for SplitN<'a, T, P>
```impl<'a, T, P> Iterator for SplitN<'a, T, P> where
P: FnMut(&T) -> bool,
type Item = &'a [T];
```

Returns an iterator over subslices separated by elements that match `pred`, limited to returning at most `n` items. The matched element is not contained in the subslices.

The last element returned, if any, will contain the remainder of the slice.

## Examples

Print the slice split once by numbers divisible by 3 (i.e., `[10, 40]`, `[20, 60, 50]`):

```let v = [10, 40, 30, 20, 60, 50];

for group in v.splitn(2, |num| *num % 3 == 0) {
println!("{:?}", group);
}```

#### `pub fn splitn_mut<F>(&mut self, n: usize, pred: F) -> SplitNMut<T, F> where    F: FnMut(&T) -> bool, `[src]

ⓘImportant traits for SplitNMut<'a, T, P>
```impl<'a, T, P> Iterator for SplitNMut<'a, T, P> where
P: FnMut(&T) -> bool,
type Item = &'a mut [T];
```

Returns an iterator over subslices separated by elements that match `pred`, limited to returning at most `n` items. The matched element is not contained in the subslices.

The last element returned, if any, will contain the remainder of the slice.

## Examples

```let mut v = [10, 40, 30, 20, 60, 50];

for group in v.splitn_mut(2, |num| *num % 3 == 0) {
group = 1;
}
assert_eq!(v, [1, 40, 30, 1, 60, 50]);```

#### `pub fn rsplitn<F>(&self, n: usize, pred: F) -> RSplitN<T, F> where    F: FnMut(&T) -> bool, `[src]

ⓘImportant traits for RSplitN<'a, T, P>
```impl<'a, T, P> Iterator for RSplitN<'a, T, P> where
P: FnMut(&T) -> bool,
type Item = &'a [T];
```

Returns an iterator over subslices separated by elements that match `pred` limited to returning at most `n` items. This starts at the end of the slice and works backwards. The matched element is not contained in the subslices.

The last element returned, if any, will contain the remainder of the slice.

## Examples

Print the slice split once, starting from the end, by numbers divisible by 3 (i.e., ``, `[10, 40, 30, 20]`):

```let v = [10, 40, 30, 20, 60, 50];

for group in v.rsplitn(2, |num| *num % 3 == 0) {
println!("{:?}", group);
}```

#### `pub fn rsplitn_mut<F>(&mut self, n: usize, pred: F) -> RSplitNMut<T, F> where    F: FnMut(&T) -> bool, `[src]

ⓘImportant traits for RSplitNMut<'a, T, P>
```impl<'a, T, P> Iterator for RSplitNMut<'a, T, P> where
P: FnMut(&T) -> bool,
type Item = &'a mut [T];
```

Returns an iterator over subslices separated by elements that match `pred` limited to returning at most `n` items. This starts at the end of the slice and works backwards. The matched element is not contained in the subslices.

The last element returned, if any, will contain the remainder of the slice.

## Examples

```let mut s = [10, 40, 30, 20, 60, 50];

for group in s.rsplitn_mut(2, |num| *num % 3 == 0) {
group = 1;
}
assert_eq!(s, [1, 40, 30, 20, 60, 1]);```

#### `pub fn contains(&self, x: &T) -> bool where    T: PartialEq<T>, `[src]

Returns `true` if the slice contains an element with the given value.

## Examples

```let v = [10, 40, 30];
assert!(v.contains(&30));
assert!(!v.contains(&50));```

#### `pub fn starts_with(&self, needle: &[T]) -> bool where    T: PartialEq<T>, `[src]

Returns `true` if `needle` is a prefix of the slice.

## Examples

```let v = [10, 40, 30];
assert!(v.starts_with(&));
assert!(v.starts_with(&[10, 40]));
assert!(!v.starts_with(&));
assert!(!v.starts_with(&[10, 50]));```

Always returns `true` if `needle` is an empty slice:

```let v = &[10, 40, 30];
assert!(v.starts_with(&[]));
let v: &[u8] = &[];
assert!(v.starts_with(&[]));```

#### `pub fn ends_with(&self, needle: &[T]) -> bool where    T: PartialEq<T>, `[src]

Returns `true` if `needle` is a suffix of the slice.

## Examples

```let v = [10, 40, 30];
assert!(v.ends_with(&));
assert!(v.ends_with(&[40, 30]));
assert!(!v.ends_with(&));
assert!(!v.ends_with(&[50, 30]));```

Always returns `true` if `needle` is an empty slice:

```let v = &[10, 40, 30];
assert!(v.ends_with(&[]));
let v: &[u8] = &[];
assert!(v.ends_with(&[]));```

Binary searches this sorted slice for a given element.

If the value is found then `Result::Ok` is returned, containing the index of the matching element. If there are multiple matches, then any one of the matches could be returned. If the value is not found then `Result::Err` is returned, containing the index where a matching element could be inserted while maintaining sorted order.

## Examples

Looks up a series of four elements. The first is found, with a uniquely determined position; the second and third are not found; the fourth could match any position in `[1, 4]`.

```let s = [0, 1, 1, 1, 1, 2, 3, 5, 8, 13, 21, 34, 55];

assert_eq!(s.binary_search(&13),  Ok(9));
assert_eq!(s.binary_search(&4),   Err(7));
assert_eq!(s.binary_search(&100), Err(13));
let r = s.binary_search(&1);
assert!(match r { Ok(1..=4) => true, _ => false, });```

#### `pub fn binary_search_by<'a, F>(&'a self, f: F) -> Result<usize, usize> where    F: FnMut(&'a T) -> Ordering, `[src]

Binary searches this sorted slice with a comparator function.

The comparator function should implement an order consistent with the sort order of the underlying slice, returning an order code that indicates whether its argument is `Less`, `Equal` or `Greater` the desired target.

If the value is found then `Result::Ok` is returned, containing the index of the matching element. If there are multiple matches, then any one of the matches could be returned. If the value is not found then `Result::Err` is returned, containing the index where a matching element could be inserted while maintaining sorted order.

## Examples

Looks up a series of four elements. The first is found, with a uniquely determined position; the second and third are not found; the fourth could match any position in `[1, 4]`.

```let s = [0, 1, 1, 1, 1, 2, 3, 5, 8, 13, 21, 34, 55];

let seek = 13;
assert_eq!(s.binary_search_by(|probe| probe.cmp(&seek)), Ok(9));
let seek = 4;
assert_eq!(s.binary_search_by(|probe| probe.cmp(&seek)), Err(7));
let seek = 100;
assert_eq!(s.binary_search_by(|probe| probe.cmp(&seek)), Err(13));
let seek = 1;
let r = s.binary_search_by(|probe| probe.cmp(&seek));
assert!(match r { Ok(1..=4) => true, _ => false, });```

#### `pub fn binary_search_by_key<'a, B, F>(    &'a self,     b: &B,     f: F) -> Result<usize, usize> where    B: Ord,    F: FnMut(&'a T) -> B, `[src]1.10.0

Binary searches this sorted slice with a key extraction function.

Assumes that the slice is sorted by the key, for instance with `sort_by_key` using the same key extraction function.

If the value is found then `Result::Ok` is returned, containing the index of the matching element. If there are multiple matches, then any one of the matches could be returned. If the value is not found then `Result::Err` is returned, containing the index where a matching element could be inserted while maintaining sorted order.

## Examples

Looks up a series of four elements in a slice of pairs sorted by their second elements. The first is found, with a uniquely determined position; the second and third are not found; the fourth could match any position in `[1, 4]`.

```let s = [(0, 0), (2, 1), (4, 1), (5, 1), (3, 1),
(1, 2), (2, 3), (4, 5), (5, 8), (3, 13),
(1, 21), (2, 34), (4, 55)];

assert_eq!(s.binary_search_by_key(&13, |&(a,b)| b),  Ok(9));
assert_eq!(s.binary_search_by_key(&4, |&(a,b)| b),   Err(7));
assert_eq!(s.binary_search_by_key(&100, |&(a,b)| b), Err(13));
let r = s.binary_search_by_key(&1, |&(a,b)| b);
assert!(match r { Ok(1..=4) => true, _ => false, });```

#### `pub fn sort_unstable(&mut self) where    T: Ord, `[src]1.20.0

Sorts the slice, but may not preserve the order of equal elements.

This sort is unstable (i.e., may reorder equal elements), in-place (i.e., does not allocate), and `O(n log n)` worst-case.

## Current implementation

The current algorithm is based on pattern-defeating quicksort by Orson Peters, which combines the fast average case of randomized quicksort with the fast worst case of heapsort, while achieving linear time on slices with certain patterns. It uses some randomization to avoid degenerate cases, but with a fixed seed to always provide deterministic behavior.

It is typically faster than stable sorting, except in a few special cases, e.g., when the slice consists of several concatenated sorted sequences.

## Examples

```let mut v = [-5, 4, 1, -3, 2];

v.sort_unstable();
assert!(v == [-5, -3, 1, 2, 4]);```

#### `pub fn sort_unstable_by<F>(&mut self, compare: F) where    F: FnMut(&T, &T) -> Ordering, `[src]1.20.0

Sorts the slice with a comparator function, but may not preserve the order of equal elements.

This sort is unstable (i.e., may reorder equal elements), in-place (i.e., does not allocate), and `O(n log n)` worst-case.

The comparator function must define a total ordering for the elements in the slice. If the ordering is not total, the order of the elements is unspecified. 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 >.

For example, while `f64` doesn't implement `Ord` because `NaN != NaN`, we can use `partial_cmp` as our sort function when we know the slice doesn't contain a `NaN`.

```let mut floats = [5f64, 4.0, 1.0, 3.0, 2.0];
floats.sort_by(|a, b| a.partial_cmp(b).unwrap());
assert_eq!(floats, [1.0, 2.0, 3.0, 4.0, 5.0]);```

## Current implementation

The current algorithm is based on pattern-defeating quicksort by Orson Peters, which combines the fast average case of randomized quicksort with the fast worst case of heapsort, while achieving linear time on slices with certain patterns. It uses some randomization to avoid degenerate cases, but with a fixed seed to always provide deterministic behavior.

It is typically faster than stable sorting, except in a few special cases, e.g., when the slice consists of several concatenated sorted sequences.

## Examples

```let mut v = [5, 4, 1, 3, 2];
v.sort_unstable_by(|a, b| a.cmp(b));
assert!(v == [1, 2, 3, 4, 5]);

// reverse sorting
v.sort_unstable_by(|a, b| b.cmp(a));
assert!(v == [5, 4, 3, 2, 1]);```

#### `pub fn sort_unstable_by_key<K, F>(&mut self, f: F) where    F: FnMut(&T) -> K,    K: Ord, `[src]1.20.0

Sorts the slice with a key extraction function, but may not preserve the order of equal elements.

This sort is unstable (i.e., may reorder equal elements), in-place (i.e., does not allocate), and `O(m n log(m n))` worst-case, where the key function is `O(m)`.

## Current implementation

The current algorithm is based on pattern-defeating quicksort by Orson Peters, which combines the fast average case of randomized quicksort with the fast worst case of heapsort, while achieving linear time on slices with certain patterns. It uses some randomization to avoid degenerate cases, but with a fixed seed to always provide deterministic behavior.

Due to its key calling strategy, `sort_unstable_by_key` is likely to be slower than `sort_by_cached_key` in cases where the key function is expensive.

## Examples

```let mut v = [-5i32, 4, 1, -3, 2];

v.sort_unstable_by_key(|k| k.abs());
assert!(v == [1, 2, -3, 4, -5]);```

#### `pub fn partition_at_index(    &mut self,     index: usize) -> (&mut [T], &mut T, &mut [T]) where    T: Ord, `[src]

🔬 This is a nightly-only experimental API. (slice_partition_at_index #55300)

Reorder the slice such that the element at `index` is at its final sorted position.

This reordering has the additional property that any value at position `i < index` will be less than or equal to any value at a position `j > index`. Additionally, this reordering is unstable (i.e. any number of equal elements may end up at position `index`), in-place (i.e. does not allocate), and `O(n)` worst-case. This function is also/ known as "kth element" in other libraries. It returns a triplet of the following values: all elements less than the one at the given index, the value at the given index, and all elements greater than the one at the given index.

## Current implementation

The current algorithm is based on the quickselect portion of the same quicksort algorithm used for `sort_unstable`.

## Panics

Panics when `index >= len()`, meaning it always panics on empty slices.

## Examples

```#![feature(slice_partition_at_index)]

let mut v = [-5i32, 4, 1, -3, 2];

// Find the median
v.partition_at_index(2);

// We are only guaranteed the slice will be one of the following, based on the way we sort
assert!(v == [-3, -5, 1, 2, 4] ||
v == [-5, -3, 1, 2, 4] ||
v == [-3, -5, 1, 4, 2] ||
v == [-5, -3, 1, 4, 2]);```

#### `pub fn partition_at_index_by<F>(    &mut self,     index: usize,     compare: F) -> (&mut [T], &mut T, &mut [T]) where    F: FnMut(&T, &T) -> Ordering, `[src]

🔬 This is a nightly-only experimental API. (slice_partition_at_index #55300)

Reorder the slice with a comparator function such that the element at `index` is at its final sorted position.

This reordering has the additional property that any value at position `i < index` will be less than or equal to any value at a position `j > index` using the comparator function. Additionally, this reordering is unstable (i.e. any number of equal elements may end up at position `index`), in-place (i.e. does not allocate), and `O(n)` worst-case. This function is also known as "kth element" in other libraries. It returns a triplet of the following values: all elements less than the one at the given index, the value at the given index, and all elements greater than the one at the given index, using the provided comparator function.

## Current implementation

The current algorithm is based on the quickselect portion of the same quicksort algorithm used for `sort_unstable`.

## Panics

Panics when `index >= len()`, meaning it always panics on empty slices.

## Examples

```#![feature(slice_partition_at_index)]

let mut v = [-5i32, 4, 1, -3, 2];

// Find the median as if the slice were sorted in descending order.
v.partition_at_index_by(2, |a, b| b.cmp(a));

// We are only guaranteed the slice will be one of the following, based on the way we sort
assert!(v == [2, 4, 1, -5, -3] ||
v == [2, 4, 1, -3, -5] ||
v == [4, 2, 1, -5, -3] ||
v == [4, 2, 1, -3, -5]);```

#### `pub fn partition_at_index_by_key<K, F>(    &mut self,     index: usize,     f: F) -> (&mut [T], &mut T, &mut [T]) where    F: FnMut(&T) -> K,    K: Ord, `[src]

🔬 This is a nightly-only experimental API. (slice_partition_at_index #55300)

Reorder the slice with a key extraction function such that the element at `index` is at its final sorted position.

This reordering has the additional property that any value at position `i < index` will be less than or equal to any value at a position `j > index` using the key extraction function. Additionally, this reordering is unstable (i.e. any number of equal elements may end up at position `index`), in-place (i.e. does not allocate), and `O(n)` worst-case. This function is also known as "kth element" in other libraries. It returns a triplet of the following values: all elements less than the one at the given index, the value at the given index, and all elements greater than the one at the given index, using the provided key extraction function.

## Current implementation

The current algorithm is based on the quickselect portion of the same quicksort algorithm used for `sort_unstable`.

## Panics

Panics when `index >= len()`, meaning it always panics on empty slices.

## Examples

```#![feature(slice_partition_at_index)]

let mut v = [-5i32, 4, 1, -3, 2];

// Return the median as if the array were sorted according to absolute value.
v.partition_at_index_by_key(2, |a| a.abs());

// We are only guaranteed the slice will be one of the following, based on the way we sort
assert!(v == [1, 2, -3, 4, -5] ||
v == [1, 2, -3, -5, 4] ||
v == [2, 1, -3, 4, -5] ||
v == [2, 1, -3, -5, 4]);```

#### `pub fn partition_dedup(&mut self) -> (&mut [T], &mut [T]) where    T: PartialEq<T>, `[src]

🔬 This is a nightly-only experimental API. (slice_partition_dedup #54279)

Moves all consecutive repeated elements to the end of the slice according to the `PartialEq` trait implementation.

Returns two slices. The first contains no consecutive repeated elements. The second contains all the duplicates in no specified order.

If the slice is sorted, the first returned slice contains no duplicates.

## Examples

```#![feature(slice_partition_dedup)]

let mut slice = [1, 2, 2, 3, 3, 2, 1, 1];

let (dedup, duplicates) = slice.partition_dedup();

assert_eq!(dedup, [1, 2, 3, 2, 1]);
assert_eq!(duplicates, [2, 3, 1]);```

#### `pub fn partition_dedup_by<F>(&mut self, same_bucket: F) -> (&mut [T], &mut [T]) where    F: FnMut(&mut T, &mut T) -> bool, `[src]

🔬 This is a nightly-only experimental API. (slice_partition_dedup #54279)

Moves all but the first of consecutive elements to the end of the slice satisfying a given equality relation.

Returns two slices. The first contains no consecutive repeated elements. The second contains all the duplicates in no specified order.

The `same_bucket` function is passed references to two elements from the slice and must determine if the elements compare equal. The elements are passed in opposite order from their order in the slice, so if `same_bucket(a, b)` returns `true`, `a` is moved at the end of the slice.

If the slice is sorted, the first returned slice contains no duplicates.

## Examples

```#![feature(slice_partition_dedup)]

let mut slice = ["foo", "Foo", "BAZ", "Bar", "bar", "baz", "BAZ"];

let (dedup, duplicates) = slice.partition_dedup_by(|a, b| a.eq_ignore_ascii_case(b));

assert_eq!(dedup, ["foo", "BAZ", "Bar", "baz"]);
assert_eq!(duplicates, ["bar", "Foo", "BAZ"]);```

#### `pub fn partition_dedup_by_key<K, F>(&mut self, key: F) -> (&mut [T], &mut [T]) where    F: FnMut(&mut T) -> K,    K: PartialEq<K>, `[src]

🔬 This is a nightly-only experimental API. (slice_partition_dedup #54279)

Moves all but the first of consecutive elements to the end of the slice that resolve to the same key.

Returns two slices. The first contains no consecutive repeated elements. The second contains all the duplicates in no specified order.

If the slice is sorted, the first returned slice contains no duplicates.

## Examples

```#![feature(slice_partition_dedup)]

let mut slice = [10, 20, 21, 30, 30, 20, 11, 13];

let (dedup, duplicates) = slice.partition_dedup_by_key(|i| *i / 10);

assert_eq!(dedup, [10, 20, 30, 20, 11]);
assert_eq!(duplicates, [21, 30, 13]);```

#### `pub fn rotate_left(&mut self, mid: usize)`[src]1.26.0

Rotates the slice in-place such that the first `mid` elements of the slice move to the end while the last `self.len() - mid` elements move to the front. After calling `rotate_left`, the element previously at index `mid` will become the first element in the slice.

## Panics

This function will panic if `mid` is greater than the length of the slice. Note that `mid == self.len()` does not panic and is a no-op rotation.

## Complexity

Takes linear (in `self.len()`) time.

## Examples

```let mut a = ['a', 'b', 'c', 'd', 'e', 'f'];
a.rotate_left(2);
assert_eq!(a, ['c', 'd', 'e', 'f', 'a', 'b']);```

Rotating a subslice:

```let mut a = ['a', 'b', 'c', 'd', 'e', 'f'];
a[1..5].rotate_left(1);
assert_eq!(a, ['a', 'c', 'd', 'e', 'b', 'f']);```

#### `pub fn rotate_right(&mut self, k: usize)`[src]1.26.0

Rotates the slice in-place such that the first `self.len() - k` elements of the slice move to the end while the last `k` elements move to the front. After calling `rotate_right`, the element previously at index `self.len() - k` will become the first element in the slice.

## Panics

This function will panic if `k` is greater than the length of the slice. Note that `k == self.len()` does not panic and is a no-op rotation.

## Complexity

Takes linear (in `self.len()`) time.

## Examples

```let mut a = ['a', 'b', 'c', 'd', 'e', 'f'];
a.rotate_right(2);
assert_eq!(a, ['e', 'f', 'a', 'b', 'c', 'd']);```

Rotate a subslice:

```let mut a = ['a', 'b', 'c', 'd', 'e', 'f'];
a[1..5].rotate_right(1);
assert_eq!(a, ['a', 'e', 'b', 'c', 'd', 'f']);```

#### `pub fn clone_from_slice(&mut self, src: &[T]) where    T: Clone, `[src]1.7.0

Copies the elements from `src` into `self`.

The length of `src` must be the same as `self`.

If `src` implements `Copy`, it can be more performant to use `copy_from_slice`.

## Panics

This function will panic if the two slices have different lengths.

## Examples

Cloning two elements from a slice into another:

```let src = [1, 2, 3, 4];
let mut dst = [0, 0];

// Because the slices have to be the same length,
// we slice the source slice from four elements
// to two. It will panic if we don't do this.
dst.clone_from_slice(&src[2..]);

assert_eq!(src, [1, 2, 3, 4]);
assert_eq!(dst, [3, 4]);```

Rust enforces that there can only be one mutable reference with no immutable references to a particular piece of data in a particular scope. Because of this, attempting to use `clone_from_slice` on a single slice will result in a compile failure:

ⓘThis example deliberately fails to compile
```let mut slice = [1, 2, 3, 4, 5];

slice[..2].clone_from_slice(&slice[3..]); // compile fail!```

To work around this, we can use `split_at_mut` to create two distinct sub-slices from a slice:

```let mut slice = [1, 2, 3, 4, 5];

{
let (left, right) = slice.split_at_mut(2);
left.clone_from_slice(&right[1..]);
}

assert_eq!(slice, [4, 5, 3, 4, 5]);```

#### `pub fn copy_from_slice(&mut self, src: &[T]) where    T: Copy, `[src]1.9.0

Copies all elements from `src` into `self`, using a memcpy.

The length of `src` must be the same as `self`.

If `src` does not implement `Copy`, use `clone_from_slice`.

## Panics

This function will panic if the two slices have different lengths.

## Examples

Copying two elements from a slice into another:

```let src = [1, 2, 3, 4];
let mut dst = [0, 0];

// Because the slices have to be the same length,
// we slice the source slice from four elements
// to two. It will panic if we don't do this.
dst.copy_from_slice(&src[2..]);

assert_eq!(src, [1, 2, 3, 4]);
assert_eq!(dst, [3, 4]);```

Rust enforces that there can only be one mutable reference with no immutable references to a particular piece of data in a particular scope. Because of this, attempting to use `copy_from_slice` on a single slice will result in a compile failure:

ⓘThis example deliberately fails to compile
```let mut slice = [1, 2, 3, 4, 5];

slice[..2].copy_from_slice(&slice[3..]); // compile fail!```

To work around this, we can use `split_at_mut` to create two distinct sub-slices from a slice:

```let mut slice = [1, 2, 3, 4, 5];

{
let (left, right) = slice.split_at_mut(2);
left.copy_from_slice(&right[1..]);
}

assert_eq!(slice, [4, 5, 3, 4, 5]);```

#### `pub fn copy_within<R>(&mut self, src: R, dest: usize) where    R: RangeBounds<usize>,    T: Copy, `[src]1.37.0

Copies elements from one part of the slice to another part of itself, using a memmove.

`src` is the range within `self` to copy from. `dest` is the starting index of the range within `self` to copy to, which will have the same length as `src`. The two ranges may overlap. The ends of the two ranges must be less than or equal to `self.len()`.

## Panics

This function will panic if either range exceeds the end of the slice, or if the end of `src` is before the start.

## Examples

Copying four bytes within a slice:

```let mut bytes = *b"Hello, World!";

bytes.copy_within(1..5, 8);

assert_eq!(&bytes, b"Hello, Wello!");```

#### `pub fn swap_with_slice(&mut self, other: &mut [T])`[src]1.27.0

Swaps all elements in `self` with those in `other`.

The length of `other` must be the same as `self`.

## Panics

This function will panic if the two slices have different lengths.

## Example

Swapping two elements across slices:

```let mut slice1 = [0, 0];
let mut slice2 = [1, 2, 3, 4];

slice1.swap_with_slice(&mut slice2[2..]);

assert_eq!(slice1, [3, 4]);
assert_eq!(slice2, [1, 2, 0, 0]);```

Rust enforces that there can only be one mutable reference to a particular piece of data in a particular scope. Because of this, attempting to use `swap_with_slice` on a single slice will result in a compile failure:

ⓘThis example deliberately fails to compile
```let mut slice = [1, 2, 3, 4, 5];
slice[..2].swap_with_slice(&mut slice[3..]); // compile fail!```

To work around this, we can use `split_at_mut` to create two distinct mutable sub-slices from a slice:

```let mut slice = [1, 2, 3, 4, 5];

{
let (left, right) = slice.split_at_mut(2);
left.swap_with_slice(&mut right[1..]);
}

assert_eq!(slice, [4, 5, 3, 1, 2]);```

#### `pub unsafe fn align_to<U>(&self) -> (&[T], &[U], &[T])`[src]1.30.0

Transmute the slice to a slice of another type, ensuring alignment of the types is maintained.

This method splits the slice into three distinct slices: prefix, correctly aligned middle slice of a new type, and the suffix slice. The method does a best effort to make the middle slice the greatest length possible for a given type and input slice, but only your algorithm's performance should depend on that, not its correctness.

This method has no purpose when either input element `T` or output element `U` are zero-sized and will return the original slice without splitting anything.

## Safety

This method is essentially a `transmute` with respect to the elements in the returned middle slice, so all the usual caveats pertaining to `transmute::<T, U>` also apply here.

## Examples

Basic usage:

```unsafe {
let bytes: [u8; 7] = [1, 2, 3, 4, 5, 6, 7];
let (prefix, shorts, suffix) = bytes.align_to::<u16>();
// less_efficient_algorithm_for_bytes(prefix);
// more_efficient_algorithm_for_aligned_shorts(shorts);
// less_efficient_algorithm_for_bytes(suffix);
}```

#### `pub unsafe fn align_to_mut<U>(&mut self) -> (&mut [T], &mut [U], &mut [T])`[src]1.30.0

Transmute the slice to a slice of another type, ensuring alignment of the types is maintained.

This method splits the slice into three distinct slices: prefix, correctly aligned middle slice of a new type, and the suffix slice. The method does a best effort to make the middle slice the greatest length possible for a given type and input slice, but only your algorithm's performance should depend on that, not its correctness.

This method has no purpose when either input element `T` or output element `U` are zero-sized and will return the original slice without splitting anything.

## Safety

This method is essentially a `transmute` with respect to the elements in the returned middle slice, so all the usual caveats pertaining to `transmute::<T, U>` also apply here.

## Examples

Basic usage:

```unsafe {
let mut bytes: [u8; 7] = [1, 2, 3, 4, 5, 6, 7];
let (prefix, shorts, suffix) = bytes.align_to_mut::<u16>();
// less_efficient_algorithm_for_bytes(prefix);
// more_efficient_algorithm_for_aligned_shorts(shorts);
// less_efficient_algorithm_for_bytes(suffix);
}```

#### `pub fn is_sorted(&self) -> bool where    T: PartialOrd<T>, `[src]

🔬 This is a nightly-only experimental API. (is_sorted #53485)new API

Checks if the elements of this slice are sorted.

That is, for each element `a` and its following element `b`, `a <= b` must hold. If the slice yields exactly zero or one element, `true` is returned.

Note that if `Self::Item` is only `PartialOrd`, but not `Ord`, the above definition implies that this function returns `false` if any two consecutive items are not comparable.

## Examples

```#![feature(is_sorted)]
let empty: [i32; 0] = [];

assert!([1, 2, 2, 9].is_sorted());
assert!(![1, 3, 2, 4].is_sorted());
assert!(.is_sorted());
assert!(empty.is_sorted());
assert!(![0.0, 1.0, std::f32::NAN].is_sorted());```

#### `pub fn is_sorted_by<F>(&self, compare: F) -> bool where    F: FnMut(&T, &T) -> Option<Ordering>, `[src]

🔬 This is a nightly-only experimental API. (is_sorted #53485)new API

Checks if the elements of this slice are sorted using the given comparator function.

Instead of using `PartialOrd::partial_cmp`, this function uses the given `compare` function to determine the ordering of two elements. Apart from that, it's equivalent to `is_sorted`; see its documentation for more information.

#### `pub fn is_sorted_by_key<F, K>(&self, f: F) -> bool where    F: FnMut(&T) -> K,    K: PartialOrd<K>, `[src]

🔬 This is a nightly-only experimental API. (is_sorted #53485)new API

Checks if the elements of this slice are sorted using the given key extraction function.

Instead of comparing the slice's elements directly, this function compares the keys of the elements, as determined by `f`. Apart from that, it's equivalent to `is_sorted`; see its documentation for more information.

## Examples

```#![feature(is_sorted)]

assert!(["c", "bb", "aaa"].is_sorted_by_key(|s| s.len()));
assert!(![-2i32, -1, 0, 3].is_sorted_by_key(|n| n.abs()));```

### `impl [u8]`[src]

#### `pub fn is_ascii(&self) -> bool`[src]1.23.0

Checks if all bytes in this slice are within the ASCII range.

#### `pub fn eq_ignore_ascii_case(&self, other: &[u8]) -> bool`[src]1.23.0

Checks that two slices are an ASCII case-insensitive match.

Same as `to_ascii_lowercase(a) == to_ascii_lowercase(b)`, but without allocating and copying temporaries.

#### `pub fn make_ascii_uppercase(&mut self)`[src]1.23.0

Converts this slice to its ASCII upper case equivalent in-place.

ASCII letters 'a' to 'z' are mapped to 'A' to 'Z', but non-ASCII letters are unchanged.

To return a new uppercased value without modifying the existing one, use `to_ascii_uppercase`.

#### `pub fn make_ascii_lowercase(&mut self)`[src]1.23.0

Converts this slice to its ASCII lower case equivalent in-place.

ASCII letters 'A' to 'Z' are mapped to 'a' to 'z', but non-ASCII letters are unchanged.

To return a new lowercased value without modifying the existing one, use `to_ascii_lowercase`.

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

#### `pub fn sort(&mut self) where    T: Ord, `[src]

Sorts the slice.

This sort is stable (i.e., does not reorder equal elements) and `O(n log n)` worst-case.

When applicable, unstable sorting is preferred because it is generally faster than stable sorting and it doesn't allocate auxiliary memory. See `sort_unstable`.

## Current implementation

The current algorithm is an adaptive, iterative merge sort inspired by timsort. It is designed to be very fast in cases where the slice is nearly sorted, or consists of two or more sorted sequences concatenated one after another.

Also, it allocates temporary storage half the size of `self`, but for short slices a non-allocating insertion sort is used instead.

## Examples

```let mut v = [-5, 4, 1, -3, 2];

v.sort();
assert!(v == [-5, -3, 1, 2, 4]);```

#### `pub fn sort_by<F>(&mut self, compare: F) where    F: FnMut(&T, &T) -> Ordering, `[src]

Sorts the slice with a comparator function.

This sort is stable (i.e., does not reorder equal elements) and `O(n log n)` worst-case.

The comparator function must define a total ordering for the elements in the slice. If the ordering is not total, the order of the elements is unspecified. 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 `>`.

For example, while `f64` doesn't implement `Ord` because `NaN != NaN`, we can use `partial_cmp` as our sort function when we know the slice doesn't contain a `NaN`.

```let mut floats = [5f64, 4.0, 1.0, 3.0, 2.0];
floats.sort_by(|a, b| a.partial_cmp(b).unwrap());
assert_eq!(floats, [1.0, 2.0, 3.0, 4.0, 5.0]);```

When applicable, unstable sorting is preferred because it is generally faster than stable sorting and it doesn't allocate auxiliary memory. See `sort_unstable_by`.

## Current implementation

The current algorithm is an adaptive, iterative merge sort inspired by timsort. It is designed to be very fast in cases where the slice is nearly sorted, or consists of two or more sorted sequences concatenated one after another.

Also, it allocates temporary storage half the size of `self`, but for short slices a non-allocating insertion sort is used instead.

## Examples

```let mut v = [5, 4, 1, 3, 2];
v.sort_by(|a, b| a.cmp(b));
assert!(v == [1, 2, 3, 4, 5]);

// reverse sorting
v.sort_by(|a, b| b.cmp(a));
assert!(v == [5, 4, 3, 2, 1]);```

#### `pub fn sort_by_key<K, F>(&mut self, f: F) where    F: FnMut(&T) -> K,    K: Ord, `[src]1.7.0

Sorts the slice with a key extraction function.

This sort is stable (i.e., does not reorder equal elements) and `O(m n log(m n))` worst-case, where the key function is `O(m)`.

For expensive key functions (e.g. functions that are not simple property accesses or basic operations), `sort_by_cached_key` is likely to be significantly faster, as it does not recompute element keys.

When applicable, unstable sorting is preferred because it is generally faster than stable sorting and it doesn't allocate auxiliary memory. See `sort_unstable_by_key`.

## Current implementation

The current algorithm is an adaptive, iterative merge sort inspired by timsort. It is designed to be very fast in cases where the slice is nearly sorted, or consists of two or more sorted sequences concatenated one after another.

Also, it allocates temporary storage half the size of `self`, but for short slices a non-allocating insertion sort is used instead.

## Examples

```let mut v = [-5i32, 4, 1, -3, 2];

v.sort_by_key(|k| k.abs());
assert!(v == [1, 2, -3, 4, -5]);```

#### `pub fn sort_by_cached_key<K, F>(&mut self, f: F) where    F: FnMut(&T) -> K,    K: Ord, `[src]1.34.0

Sorts the slice with a key extraction function.

During sorting, the key function is called only once per element.

This sort is stable (i.e., does not reorder equal elements) and `O(m n + n log n)` worst-case, where the key function is `O(m)`.

For simple key functions (e.g., functions that are property accesses or basic operations), `sort_by_key` is likely to be faster.

## Current implementation

The current algorithm is based on pattern-defeating quicksort by Orson Peters, which combines the fast average case of randomized quicksort with the fast worst case of heapsort, while achieving linear time on slices with certain patterns. It uses some randomization to avoid degenerate cases, but with a fixed seed to always provide deterministic behavior.

In the worst case, the algorithm allocates temporary storage in a `Vec<(K, usize)>` the length of the slice.

## Examples

```let mut v = [-5i32, 4, 32, -3, 2];

v.sort_by_cached_key(|k| k.to_string());
assert!(v == [-3, -5, 2, 32, 4]);```

#### `pub fn to_vec(&self) -> Vec<T> where    T: Clone, `[src]

ⓘImportant traits for Vec<u8>
```impl Write for Vec<u8>
```

Copies `self` into a new `Vec`.

## Examples

```let s = [10, 40, 30];
let x = s.to_vec();
// Here, `s` and `x` can be modified independently.```

#### `pub fn into_vec(self: Box<[T]>) -> Vec<T>`[src]

ⓘImportant traits for Vec<u8>
```impl Write for Vec<u8>
```

Converts `self` into a vector without clones or allocation.

The resulting vector can be converted back into a box via `Vec<T>`'s `into_boxed_slice` method.

## Examples

```let s: Box<[i32]> = Box::new([10, 40, 30]);
let x = s.into_vec();
// `s` cannot be used anymore because it has been converted into `x`.

assert_eq!(x, vec![10, 40, 30]);```

#### `pub fn repeat(&self, n: usize) -> Vec<T> where    T: Copy, `[src]

ⓘImportant traits for Vec<u8>
```impl Write for Vec<u8>
```
🔬 This is a nightly-only experimental API. (repeat_generic_slice #48784)it's on str, why not on slice?

Creates a vector by repeating a slice `n` times.

## Panics

This function will panic if the capacity would overflow.

## Examples

Basic usage:

```#![feature(repeat_generic_slice)]

fn main() {
assert_eq!([1, 2].repeat(3), vec![1, 2, 1, 2, 1, 2]);
}```

A panic upon overflow:

```#![feature(repeat_generic_slice)]
fn main() {
// this will panic at runtime
b"0123456789abcdef".repeat(usize::max_value());
}```

### `impl [u8]`[src]

#### `pub fn to_ascii_uppercase(&self) -> Vec<u8>`[src]1.23.0

ⓘImportant traits for Vec<u8>
```impl Write for Vec<u8>
```

Returns a vector containing a copy of this slice where each byte is mapped to its ASCII upper case equivalent.

ASCII letters 'a' to 'z' are mapped to 'A' to 'Z', but non-ASCII letters are unchanged.

To uppercase the value in-place, use `make_ascii_uppercase`.

#### `pub fn to_ascii_lowercase(&self) -> Vec<u8>`[src]1.23.0

ⓘImportant traits for Vec<u8>
```impl Write for Vec<u8>
```

Returns a vector containing a copy of this slice where each byte is mapped to its ASCII lower case equivalent.

ASCII letters 'A' to 'Z' are mapped to 'a' to 'z', but non-ASCII letters are unchanged.

To lowercase the value in-place, use `make_ascii_lowercase`.

## Trait Implementations

### `impl<T, I> Index<I> for [T] where    I: SliceIndex<[T]>, `[src]

#### `type Output = <I as SliceIndex<[T]>>::Output`

The returned type after indexing.

### `impl<'_, T> Default for &'_ [T]`[src]

#### `fn default() -> &'_ [T]`[src]

ⓘImportant traits for &'_ [u8]
```impl<'_> Read for &'_ [u8]
impl<'_> Write for &'_ mut [u8]
```

Creates an empty slice.

### `impl<'_, T> Default for &'_ mut [T]`[src]1.5.0

#### `fn default() -> &'_ mut [T]`[src]

ⓘImportant traits for &'_ [u8]
```impl<'_> Read for &'_ [u8]
impl<'_> Write for &'_ mut [u8]
```

Creates a mutable empty slice.

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

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

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

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

ⓘImportant traits for &'_ [u8]
```impl<'_> Read for &'_ [u8]
impl<'_> Write for &'_ mut [u8]
```

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

Implements comparison of vectors lexicographically.

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

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

#### `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

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

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

#### `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<'a, T> IntoIterator for &'a [T]`[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?

ⓘImportant traits for Iter<'a, T>
```impl<'a, T> Iterator for Iter<'a, T>
type Item = &'a T;
```

### `impl<'a, T> IntoIterator for &'a mut [T]`[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?

ⓘImportant traits for IterMut<'a, T>
```impl<'a, T> Iterator for IterMut<'a, T>
type Item = &'a mut T;
```

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

Implements comparison of vectors lexicographically.

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

Compares and returns the maximum of two values. Read more

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

Compares and returns the minimum of two values. Read more

#### `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<'a, 'b> Pattern<'a> for &'b [char]`[src]

Searches for chars that are equal to any of the chars in the array

#### `type Searcher = CharSliceSearcher<'a, 'b>`

🔬 This is a nightly-only experimental API. (pattern #27721)API not fully fleshed out and ready to be stabilized

Associated searcher for this pattern

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

ⓘImportant traits for &'_ [u8]
```impl<'_> Read for &'_ [u8]
impl<'_> Write for &'_ mut [u8]
```

### `impl<T, V> SliceConcatExt<T> for [V] where    T: Clone,    V: Borrow<[T]>, `[src]

#### `type Output = Vec<T>`

🔬 This is a nightly-only experimental API. (slice_concat_ext #27747)trait should not have to exist

The resulting type after concatenation

ⓘImportant traits for Vec<u8>
```impl Write for Vec<u8>
```
ⓘImportant traits for Vec<u8>
```impl Write for Vec<u8>
```

#### `fn connect(&self, sep: &T) -> Self::Output`[src]

Deprecated since 1.3.0: renamed to join

Flattens a slice of `T` into a single value `Self::Output`, placing a given separator between each. Read more

### `impl<S> SliceConcatExt<str> for [S] where    S: Borrow<str>, `[src]

#### `type Output = String`

🔬 This is a nightly-only experimental API. (slice_concat_ext #27747)trait should not have to exist

The resulting type after concatenation

#### `fn connect(&self, sep: &T) -> Self::Output`[src]

Deprecated since 1.3.0: renamed to join

Flattens a slice of `T` into a single value `Self::Output`, placing a given separator between each. Read more

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

#### `type Owned = Vec<T>`

The resulting type after obtaining ownership.

ⓘImportant traits for Vec<u8>
```impl Write for Vec<u8>
```

### `impl AsciiExt for [u8]`[src]

#### `type Owned = Vec<u8>`

Deprecated since 1.26.0: use inherent methods instead

Container type for copied ASCII characters.

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

Read is implemented for `&[u8]` by copying from the slice.

Note that reading updates the slice to point to the yet unread part. The slice will be empty when EOF is reached.

#### `fn read_to_string(&mut self, buf: &mut String) -> Result<usize>`[src]

Read all bytes until EOF in this source, appending them to `buf`. Read more

#### `fn by_ref(&mut self) -> &mut Self where    Self: Sized, `[src]

ⓘImportant traits for &'_ mut F
```impl<'_, F> Future for &'_ mut F where
F: Unpin + Future + ?Sized,
type Output = <F as Future>::Output;
impl<'_, I> Iterator for &'_ mut I where
I: Iterator + ?Sized,
type Item = <I as Iterator>::Item;
impl<'_, W: Write + ?Sized> Write for &'_ mut W
```

Creates a "by reference" adaptor for this instance of `Read`. Read more

#### `fn bytes(self) -> Bytes<Self> where    Self: Sized, `[src]

ⓘImportant traits for Bytes<R>
```impl<R: Read> Iterator for Bytes<R>
type Item = Result<u8>;
```

Transforms this `Read` instance to an [`Iterator`] over its bytes. Read more

#### `fn chain<R: Read>(self, next: R) -> Chain<Self, R> where    Self: Sized, `[src]

ⓘImportant traits for Chain<T, U>
```impl<T: Read, U: Read> Read for Chain<T, U>
```

Creates an adaptor which will chain this stream with another. Read more

#### `fn take(self, limit: u64) -> Take<Self> where    Self: Sized, `[src]

ⓘImportant traits for Take<T>
```impl<T: Read> Read for Take<T>
```

Creates an adaptor which will read at most `limit` bytes from it. Read more

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

Write is implemented for `&mut [u8]` by copying into the slice, overwriting its data.

Note that writing updates the slice to point to the yet unwritten part. The slice will be empty when it has been completely overwritten.

#### `fn write_fmt(&mut self, fmt: Arguments) -> Result<()>`[src]

Writes a formatted string into this writer, returning any error encountered. Read more

#### `fn by_ref(&mut self) -> &mut Self where    Self: Sized, `[src]

ⓘImportant traits for &'_ mut F
```impl<'_, F> Future for &'_ mut F where
F: Unpin + Future + ?Sized,
type Output = <F as Future>::Output;
impl<'_, I> Iterator for &'_ mut I where
I: Iterator + ?Sized,
type Item = <I as Iterator>::Item;
impl<'_, W: Write + ?Sized> Write for &'_ mut W
```

Creates a "by reference" adaptor for this instance of `Write`. Read more

### `impl<'_> BufRead for &'_ [u8]`[src]

#### `fn read_until(&mut self, byte: u8, buf: &mut Vec<u8>) -> Result<usize>`[src]

Read all bytes into `buf` until the delimiter `byte` or EOF is reached. Read more

#### `fn read_line(&mut self, buf: &mut String) -> Result<usize>`[src]

Read all bytes until a newline (the 0xA byte) is reached, and append them to the provided buffer. Read more

#### `fn split(self, byte: u8) -> Split<Self> where    Self: Sized, `[src]

ⓘImportant traits for Split<B>
```impl<B: BufRead> Iterator for Split<B>
type Item = Result<Vec<u8>>;
```

Returns an iterator over the contents of this reader split on the byte `byte`. Read more

#### `fn lines(self) -> Lines<Self> where    Self: Sized, `[src]

ⓘImportant traits for Lines<B>
```impl<B: BufRead> Iterator for Lines<B>
type Item = Result<String>;
```

### `impl<'a> ToSocketAddrs for &'a [SocketAddr]`[src]1.8.0

#### `type Iter = Cloned<Iter<'a, SocketAddr>>`

Returned iterator over socket addresses which this type may correspond to. Read more

## Blanket Implementations

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

ⓘImportant traits for &'_ mut F
```impl<'_, F> Future for &'_ mut F where
F: Unpin + Future + ?Sized,
type Output = <F as Future>::Output;
impl<'_, I> Iterator for &'_ mut I where
I: Iterator + ?Sized,
type Item = <I as Iterator>::Item;
impl<'_, W: Write + ?Sized> Write for &'_ mut W
```

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

ⓘImportant traits for &'_ mut F
```impl<'_, F> Future for &'_ mut F where
F: Unpin + Future + ?Sized,
type Output = <F as Future>::Output;
impl<'_, I> Iterator for &'_ mut I where
I: Iterator + ?Sized,
type Item = <I as Iterator>::Item;
impl<'_, W: Write + ?Sized> Write for &'_ mut W
```

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

#### `type Owned = T`

The resulting type after obtaining ownership.

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

ⓘImportant traits for &'_ mut F
```impl<'_, F> Future for &'_ mut F where
F: Unpin + Future + ?Sized,
type Output = <F as Future>::Output;
impl<'_, I> Iterator for &'_ mut I where
I: Iterator + ?Sized,
type Item = <I as Iterator>::Item;
impl<'_, W: Write + ?Sized> Write for &'_ mut W
```

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

ⓘImportant traits for &'_ mut F
```impl<'_, F> Future for &'_ mut F where
F: Unpin + Future + ?Sized,
type Output = <F as Future>::Output;
impl<'_, I> Iterator for &'_ mut I where
I: Iterator + ?Sized,
type Item = <I as Iterator>::Item;
impl<'_, W: Write + ?Sized> Write for &'_ mut W
```

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

#### `type Owned = T`

The resulting type after obtaining ownership.

© 2010 The Rust Project Developers