Struct std::vec::Vec
[−]
[src]
pub struct Vec<T> {
// some fields omitted
}A growable list type, written Vec<T> but pronounced 'vector.'
Examples
fn main() { let mut vec = Vec::new(); vec.push(1); vec.push(2); assert_eq!(vec.len(), 2); assert_eq!(vec[0], 1); assert_eq!(vec.pop(), Some(2)); assert_eq!(vec.len(), 1); vec[0] = 7; assert_eq!(vec[0], 7); vec.extend([1, 2, 3].iter().cloned()); for x in &vec { println!("{}", x); } assert_eq!(vec, [7, 1, 2, 3]); }let mut vec = Vec::new(); vec.push(1); vec.push(2); assert_eq!(vec.len(), 2); assert_eq!(vec[0], 1); assert_eq!(vec.pop(), Some(2)); assert_eq!(vec.len(), 1); vec[0] = 7; assert_eq!(vec[0], 7); vec.extend([1, 2, 3].iter().cloned()); for x in &vec { println!("{}", x); } assert_eq!(vec, [7, 1, 2, 3]);
The vec! macro is provided to make initialization more convenient:
let mut vec = vec![1, 2, 3]; vec.push(4); assert_eq!(vec, [1, 2, 3, 4]);
It can also initialize each element of a Vec<T> with a given value:
let vec = vec![0; 5]; assert_eq!(vec, [0, 0, 0, 0, 0]);
Use a Vec<T> as an efficient stack:
let mut stack = Vec::new(); stack.push(1); stack.push(2); stack.push(3); while let Some(top) = stack.pop() { // Prints 3, 2, 1 println!("{}", top); }
Capacity and reallocation
The capacity of a vector is the amount of space allocated for any future elements that will be added onto the vector. This is not to be confused with the length of a vector, which specifies the number of actual elements within the vector. If a vector's length exceeds its capacity, its capacity will automatically be increased, but its elements will have to be reallocated.
For example, a vector with capacity 10 and length 0 would be an empty vector
with space for 10 more elements. Pushing 10 or fewer elements onto the
vector will not change its capacity or cause reallocation to occur. However,
if the vector's length is increased to 11, it will have to reallocate, which
can be slow. For this reason, it is recommended to use Vec::with_capacity
whenever possible to specify how big the vector is expected to get.
Guarantees
Due to its incredibly fundamental nature, Vec makes a lot of guarantees
about its design. This ensures that it's as low-overhead as possible in
the general case, and can be correctly manipulated in primitive ways
by unsafe code. Note that these guarantees refer to an unqualified Vec<T>.
If additional type parameters are added (e.g. to support custom allocators),
overriding their defaults may change the behavior.
Most fundamentally, Vec is and always will be a (pointer, capacity, length) triplet. No more, no less. The order of these fields is completely unspecified, and you should use the appropriate methods to modify these. The pointer will never be null, so this type is null-pointer-optimized.
However, the pointer may not actually point to allocated memory. In particular,
if you construct a Vec with capacity 0 via Vec::new(), vec![],
Vec::with_capacity(0), or by calling shrink_to_fit() on an empty Vec, it
will not allocate memory. Similarly, if you store zero-sized types inside
a Vec, it will not allocate space for them. Note that in this case the
Vec may not report a capacity() of 0. Vec will allocate if and only
if mem::size_of::<T>() * capacity() > 0. In general, Vec's allocation
details are subtle enough that it is strongly recommended that you only
free memory allocated by a Vec by creating a new Vec and dropping it.
If a Vec has allocated memory, then the memory it points to is on the heap
(as defined by the allocator Rust is configured to use by default), and its
pointer points to len() initialized elements in order (what you would see
if you coerced it to a slice), followed by capacity() - len() logically
uninitialized elements.
Vec will never perform a "small optimization" where elements are actually stored on the stack for two reasons:
It would make it more difficult for unsafe code to correctly manipulate a Vec. The contents of a Vec wouldn't have a stable address if it were only moved, and it would be more difficult to determine if a Vec had actually allocated memory.
It would penalize the general case, incurring an additional branch on every access.
Vec will never automatically shrink itself, even if completely empty. This
ensures no unnecessary allocations or deallocations occur. Emptying a Vec
and then filling it back up to the same len() should incur no calls to
the allocator. If you wish to free up unused memory, use shrink_to_fit.
push and insert will never (re)allocate if the reported capacity is
sufficient. push and insert will (re)allocate if len() == capacity().
That is, the reported capacity is completely accurate, and can be relied on.
It can even be used to manually free the memory allocated by a Vec if
desired. Bulk insertion methods may reallocate, even when not necessary.
Vec does not guarantee any particular growth strategy when reallocating
when full, nor when reserve is called. The current strategy is basic
and it may prove desirable to use a non-constant growth factor. Whatever
strategy is used will of course guarantee O(1) amortized push.
vec![x; n], vec![a, b, c, d], and Vec::with_capacity(n), will all
produce a Vec with exactly the requested capacity. If len() == capacity(),
(as is the case for the vec! macro), then a Vec<T> can be converted
to and from a Box<[T]> without reallocating or moving the elements.
Vec will not specifically overwrite any data that is removed from it, but also won't specifically preserve it. Its uninitialized memory is scratch space that it may use however it wants. It will generally just do whatever is most efficient or otherwise easy to implement. Do not rely on removed data to be erased for security purposes. Even if you drop a Vec, its buffer may simply be reused by another Vec. Even if you zero a Vec's memory first, that may not actually happen because the optimizer does not consider this a side-effect that must be preserved.
Vec does not currently guarantee the order in which elements are dropped (the order has changed in the past, and may change again).
Methods
impl<T> Vec<T>
fn new() -> Vec<T>
Constructs a new, empty Vec<T>.
The vector will not allocate until elements are pushed onto it.
Examples
fn main() { #![allow(unused_mut)] let mut vec: Vec<i32> = Vec::new(); }let mut vec: Vec<i32> = Vec::new();
fn with_capacity(capacity: usize) -> Vec<T>
Constructs a new, empty Vec<T> with the specified capacity.
The vector will be able to hold exactly capacity elements without
reallocating. If capacity is 0, the vector will not allocate.
It is important to note that this function does not specify the length
of the returned vector, but only the capacity. (For an explanation of
the difference between length and capacity, see the main Vec<T> docs
above, 'Capacity and reallocation'.)
Examples
fn main() { let mut vec = Vec::with_capacity(10); // The vector contains no items, even though it has capacity for more assert_eq!(vec.len(), 0); // These are all done without reallocating... for i in 0..10 { vec.push(i); } // ...but this may make the vector reallocate vec.push(11); }let mut vec = Vec::with_capacity(10); // The vector contains no items, even though it has capacity for more assert_eq!(vec.len(), 0); // These are all done without reallocating... for i in 0..10 { vec.push(i); } // ...but this may make the vector reallocate vec.push(11);
unsafe fn from_raw_parts(ptr: *mut T, length: usize, capacity: usize) -> Vec<T>
Creates a Vec<T> directly from the raw components of another vector.
Safety
This is highly unsafe, due to the number of invariants that aren't checked:
ptrneeds to have been previously allocated viaString/Vec<T>(at least, it's highly likely to be incorrect if it wasn't).lengthneeds to be the length that less than or equal tocapacity.capacityneeds to be the capacity that the pointer was allocated with.
Violating these may cause problems like corrupting the allocator's internal datastructures.
Examples
use std::ptr; use std::mem; fn main() { let mut v = vec![1, 2, 3]; // Pull out the various important pieces of information about `v` let p = v.as_mut_ptr(); let len = v.len(); let cap = v.capacity(); unsafe { // Cast `v` into the void: no destructor run, so we are in // complete control of the allocation to which `p` points. mem::forget(v); // Overwrite memory with 4, 5, 6 for i in 0..len as isize { ptr::write(p.offset(i), 4 + i); } // Put everything back together into a Vec let rebuilt = Vec::from_raw_parts(p, len, cap); assert_eq!(rebuilt, [4, 5, 6]); } }use std::ptr; use std::mem; fn main() { let mut v = vec![1, 2, 3]; // Pull out the various important pieces of information about `v` let p = v.as_mut_ptr(); let len = v.len(); let cap = v.capacity(); unsafe { // Cast `v` into the void: no destructor run, so we are in // complete control of the allocation to which `p` points. mem::forget(v); // Overwrite memory with 4, 5, 6 for i in 0..len as isize { ptr::write(p.offset(i), 4 + i); } // Put everything back together into a Vec let rebuilt = Vec::from_raw_parts(p, len, cap); assert_eq!(rebuilt, [4, 5, 6]); } }
fn capacity(&self) -> usize
Returns the number of elements the vector can hold without reallocating.
Examples
fn main() { let vec: Vec<i32> = Vec::with_capacity(10); assert_eq!(vec.capacity(), 10); }let vec: Vec<i32> = Vec::with_capacity(10); assert_eq!(vec.capacity(), 10);
fn reserve(&mut self, additional: usize)
Reserves capacity for at least additional more elements to be inserted
in the given Vec<T>. The collection may reserve more space to avoid
frequent reallocations.
Panics
Panics if the new capacity overflows usize.
Examples
fn main() { let mut vec = vec![1]; vec.reserve(10); assert!(vec.capacity() >= 11); }let mut vec = vec![1]; vec.reserve(10); assert!(vec.capacity() >= 11);
fn reserve_exact(&mut self, additional: usize)
Reserves the minimum capacity for exactly additional more elements to
be inserted in the given Vec<T>. Does nothing if the capacity is already
sufficient.
Note that the allocator may give the collection more space than it
requests. Therefore capacity can not be relied upon to be precisely
minimal. Prefer reserve if future insertions are expected.
Panics
Panics if the new capacity overflows usize.
Examples
fn main() { let mut vec = vec![1]; vec.reserve_exact(10); assert!(vec.capacity() >= 11); }let mut vec = vec![1]; vec.reserve_exact(10); assert!(vec.capacity() >= 11);
fn shrink_to_fit(&mut self)
Shrinks the capacity of the vector as much as possible.
It will drop down as close as possible to the length but the allocator may still inform the vector that there is space for a few more elements.
Examples
fn main() { let mut vec = Vec::with_capacity(10); vec.extend([1, 2, 3].iter().cloned()); assert_eq!(vec.capacity(), 10); vec.shrink_to_fit(); assert!(vec.capacity() >= 3); }let mut vec = Vec::with_capacity(10); vec.extend([1, 2, 3].iter().cloned()); assert_eq!(vec.capacity(), 10); vec.shrink_to_fit(); assert!(vec.capacity() >= 3);
fn into_boxed_slice(self) -> Box<[T]>
Converts the vector into Box<[T]>.
Note that this will drop any excess capacity. Calling this and
converting back to a vector with into_vec() is equivalent to calling
shrink_to_fit().
fn truncate(&mut self, len: usize)
Shorten a vector to be len elements long, dropping excess elements.
If len is greater than the vector's current length, this has no
effect.
Examples
fn main() { let mut vec = vec![1, 2, 3, 4, 5]; vec.truncate(2); assert_eq!(vec, [1, 2]); }let mut vec = vec![1, 2, 3, 4, 5]; vec.truncate(2); assert_eq!(vec, [1, 2]);
fn as_slice(&self) -> &[T]
Extracts a slice containing the entire vector.
Equivalent to &s[..].
fn as_mut_slice(&mut self) -> &mut [T]
Extracts a mutable slice of the entire vector.
Equivalent to &mut s[..].
unsafe fn set_len(&mut self, len: usize)
Sets the length of a vector.
This will explicitly set the size of the vector, without actually modifying its buffers, so it is up to the caller to ensure that the vector is actually the specified size.
Examples
fn main() { let mut v = vec![1, 2, 3, 4]; unsafe { v.set_len(1); } }let mut v = vec![1, 2, 3, 4]; unsafe { v.set_len(1); }
fn swap_remove(&mut self, index: usize) -> T
Removes an element from anywhere in the vector and return it, replacing it with the last element.
This does not preserve ordering, but is O(1).
Panics
Panics if index is out of bounds.
Examples
fn main() { let mut v = vec!["foo", "bar", "baz", "qux"]; assert_eq!(v.swap_remove(1), "bar"); assert_eq!(v, ["foo", "qux", "baz"]); assert_eq!(v.swap_remove(0), "foo"); assert_eq!(v, ["baz", "qux"]); }let mut v = vec!["foo", "bar", "baz", "qux"]; assert_eq!(v.swap_remove(1), "bar"); assert_eq!(v, ["foo", "qux", "baz"]); assert_eq!(v.swap_remove(0), "foo"); assert_eq!(v, ["baz", "qux"]);
fn insert(&mut self, index: usize, element: T)
Inserts an element at position index within the vector, shifting all
elements after position i one position to the right.
Panics
Panics if index is greater than the vector's length.
Examples
fn main() { let mut vec = vec![1, 2, 3]; vec.insert(1, 4); assert_eq!(vec, [1, 4, 2, 3]); vec.insert(4, 5); assert_eq!(vec, [1, 4, 2, 3, 5]); }let mut vec = vec![1, 2, 3]; vec.insert(1, 4); assert_eq!(vec, [1, 4, 2, 3]); vec.insert(4, 5); assert_eq!(vec, [1, 4, 2, 3, 5]);
fn remove(&mut self, index: usize) -> T
Removes and returns the element at position index within the vector,
shifting all elements after position index one position to the left.
Panics
Panics if index is out of bounds.
Examples
fn main() { let mut v = vec![1, 2, 3]; assert_eq!(v.remove(1), 2); assert_eq!(v, [1, 3]); }let mut v = vec![1, 2, 3]; assert_eq!(v.remove(1), 2); assert_eq!(v, [1, 3]);
fn retain<F>(&mut self, f: F) where F: FnMut(&T) -> bool
Retains only the elements specified by the predicate.
In other words, remove all elements e such that f(&e) returns false.
This method operates in place and preserves the order of the retained
elements.
Examples
fn main() { let mut vec = vec![1, 2, 3, 4]; vec.retain(|&x| x%2 == 0); assert_eq!(vec, [2, 4]); }let mut vec = vec![1, 2, 3, 4]; vec.retain(|&x| x%2 == 0); assert_eq!(vec, [2, 4]);
fn push(&mut self, value: T)
Appends an element to the back of a collection.
Panics
Panics if the number of elements in the vector overflows a usize.
Examples
fn main() { let mut vec = vec![1, 2]; vec.push(3); assert_eq!(vec, [1, 2, 3]); }let mut vec = vec![1, 2]; vec.push(3); assert_eq!(vec, [1, 2, 3]);
fn pop(&mut self) -> Option<T>
Removes the last element from a vector and returns it, or None if it
is empty.
Examples
fn main() { let mut vec = vec![1, 2, 3]; assert_eq!(vec.pop(), Some(3)); assert_eq!(vec, [1, 2]); }let mut vec = vec![1, 2, 3]; assert_eq!(vec.pop(), Some(3)); assert_eq!(vec, [1, 2]);
fn append(&mut self, other: &mut Vec<T>)
Moves all the elements of other into Self, leaving other empty.
Panics
Panics if the number of elements in the vector overflows a usize.
Examples
fn main() { let mut vec = vec![1, 2, 3]; let mut vec2 = vec![4, 5, 6]; vec.append(&mut vec2); assert_eq!(vec, [1, 2, 3, 4, 5, 6]); assert_eq!(vec2, []); }let mut vec = vec![1, 2, 3]; let mut vec2 = vec![4, 5, 6]; vec.append(&mut vec2); assert_eq!(vec, [1, 2, 3, 4, 5, 6]); assert_eq!(vec2, []);
fn drain<R>(&mut self, range: R) -> Drain<T> where R: RangeArgument<usize>
Create a draining iterator that removes the specified range in the vector and yields the removed items from start to end. The element range is removed even if the iterator is not consumed until the end.
Note: It is unspecified how many elements are removed from the vector,
if the Drain value is leaked.
Panics
Panics if the starting point is greater than the end point or if the end point is greater than the length of the vector.
Examples
fn main() { // Draining using `..` clears the whole vector. let mut v = vec![1, 2, 3]; let u: Vec<_> = v.drain(..).collect(); assert_eq!(v, &[]); assert_eq!(u, &[1, 2, 3]); }// Draining using `..` clears the whole vector. let mut v = vec![1, 2, 3]; let u: Vec<_> = v.drain(..).collect(); assert_eq!(v, &[]); assert_eq!(u, &[1, 2, 3]);
fn clear(&mut self)
Clears the vector, removing all values.
Examples
fn main() { let mut v = vec![1, 2, 3]; v.clear(); assert!(v.is_empty()); }let mut v = vec![1, 2, 3]; v.clear(); assert!(v.is_empty());
fn len(&self) -> usize
Returns the number of elements in the vector.
Examples
fn main() { let a = vec![1, 2, 3]; assert_eq!(a.len(), 3); }let a = vec![1, 2, 3]; assert_eq!(a.len(), 3);
fn is_empty(&self) -> bool
Returns true if the vector contains no elements.
Examples
fn main() { let mut v = Vec::new(); assert!(v.is_empty()); v.push(1); assert!(!v.is_empty()); }let mut v = Vec::new(); assert!(v.is_empty()); v.push(1); assert!(!v.is_empty());
fn split_off(&mut self, at: usize) -> Vec<T>
Splits the collection into two at the given index.
Returns a newly allocated Self. self contains elements [0, at),
and the returned Self contains elements [at, len).
Note that the capacity of self does not change.
Panics
Panics if at > len.
Examples
fn main() { let mut vec = vec![1,2,3]; let vec2 = vec.split_off(1); assert_eq!(vec, [1]); assert_eq!(vec2, [2, 3]); }let mut vec = vec![1,2,3]; let vec2 = vec.split_off(1); assert_eq!(vec, [1]); assert_eq!(vec2, [2, 3]);
impl<T> Vec<T> where T: Clone
fn resize(&mut self, new_len: usize, value: T)
Resizes the Vec in-place so that len() is equal to new_len.
If new_len is greater than len(), the Vec is extended by the
difference, with each additional slot filled with value.
If new_len is less than len(), the Vec is simply truncated.
Examples
fn main() { let mut vec = vec!["hello"]; vec.resize(3, "world"); assert_eq!(vec, ["hello", "world", "world"]); let mut vec = vec![1, 2, 3, 4]; vec.resize(2, 0); assert_eq!(vec, [1, 2]); }let mut vec = vec!["hello"]; vec.resize(3, "world"); assert_eq!(vec, ["hello", "world", "world"]); let mut vec = vec![1, 2, 3, 4]; vec.resize(2, 0); assert_eq!(vec, [1, 2]);
fn push_all(&mut self, other: &[T])
: renamed to extend_from_slice
fn extend_from_slice(&mut self, other: &[T])
Appends all elements in a slice to the Vec.
Iterates over the slice other, clones each element, and then appends
it to this Vec. The other vector is traversed in-order.
Note that this function is same as extend except that it is
specialized to work with slices instead. If and when Rust gets
specialization this function will likely be deprecated (but still
available).
Examples
fn main() { let mut vec = vec![1]; vec.extend_from_slice(&[2, 3, 4]); assert_eq!(vec, [1, 2, 3, 4]); }let mut vec = vec![1]; vec.extend_from_slice(&[2, 3, 4]); assert_eq!(vec, [1, 2, 3, 4]);
impl<T> Vec<T> where T: PartialEq<T>
fn dedup(&mut self)
Removes consecutive repeated elements in the vector.
If the vector is sorted, this removes all duplicates.
Examples
fn main() { let mut vec = vec![1, 2, 2, 3, 2]; vec.dedup(); assert_eq!(vec, [1, 2, 3, 2]); }let mut vec = vec![1, 2, 2, 3, 2]; vec.dedup(); assert_eq!(vec, [1, 2, 3, 2]);
Methods from Deref<Target=[T]>
fn len(&self) -> usize
Returns the number of elements in the slice.
Example
fn main() { let a = [1, 2, 3]; assert_eq!(a.len(), 3); }let a = [1, 2, 3]; assert_eq!(a.len(), 3);
fn is_empty(&self) -> bool
Returns true if the slice has a length of 0
Example
fn main() { let a = [1, 2, 3]; assert!(!a.is_empty()); }let a = [1, 2, 3]; assert!(!a.is_empty());
fn first(&self) -> Option<&T>
Returns the first element of a slice, or None if it is empty.
Examples
fn main() { let v = [10, 40, 30]; assert_eq!(Some(&10), v.first()); let w: &[i32] = &[]; assert_eq!(None, w.first()); }let v = [10, 40, 30]; assert_eq!(Some(&10), v.first()); let w: &[i32] = &[]; assert_eq!(None, w.first());
fn first_mut(&mut self) -> Option<&mut T>
Returns a mutable pointer to the first element of a slice, or None if it is empty
fn split_first(&self) -> Option<(&T, &[T])>
Returns the first and all the rest of the elements of a slice.
fn split_first_mut(&mut self) -> Option<(&mut T, &mut [T])>
Returns the first and all the rest of the elements of a slice.
fn split_last(&self) -> Option<(&T, &[T])>
Returns the last and all the rest of the elements of a slice.
fn split_last_mut(&mut self) -> Option<(&mut T, &mut [T])>
Returns the last and all the rest of the elements of a slice.
fn last(&self) -> Option<&T>
Returns the last element of a slice, or None if it is empty.
Examples
fn main() { let v = [10, 40, 30]; assert_eq!(Some(&30), v.last()); let w: &[i32] = &[]; assert_eq!(None, w.last()); }let v = [10, 40, 30]; assert_eq!(Some(&30), v.last()); let w: &[i32] = &[]; assert_eq!(None, w.last());
fn last_mut(&mut self) -> Option<&mut T>
Returns a mutable pointer to the last item in the slice.
fn get(&self, index: usize) -> Option<&T>
Returns the element of a slice at the given index, or None if the
index is out of bounds.
Examples
fn main() { let v = [10, 40, 30]; assert_eq!(Some(&40), v.get(1)); assert_eq!(None, v.get(3)); }let v = [10, 40, 30]; assert_eq!(Some(&40), v.get(1)); assert_eq!(None, v.get(3));
fn get_mut(&mut self, index: usize) -> Option<&mut T>
Returns a mutable reference to the element at the given index,
or None if the index is out of bounds
unsafe fn get_unchecked(&self, index: usize) -> &T
Returns a pointer to the element at the given index, without doing bounds checking.
unsafe fn get_unchecked_mut(&mut self, index: usize) -> &mut T
Returns an unsafe mutable pointer to the element in index
fn as_ptr(&self) -> *const T
Returns an 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.
Modifying the slice may cause its buffer to be reallocated, which would also make any pointers to it invalid.
fn as_mut_ptr(&mut self) -> *mut T
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 slice may cause its buffer to be reallocated, which would also make any pointers to it invalid.
fn swap(&mut self, a: usize, b: usize)
Swaps two elements in a 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.
Example
fn main() { let mut v = ["a", "b", "c", "d"]; v.swap(1, 3); assert!(v == ["a", "d", "c", "b"]); }let mut v = ["a", "b", "c", "d"]; v.swap(1, 3); assert!(v == ["a", "d", "c", "b"]);
fn reverse(&mut self)
Reverse the order of elements in a slice, in place.
Example
fn main() { let mut v = [1, 2, 3]; v.reverse(); assert!(v == [3, 2, 1]); }let mut v = [1, 2, 3]; v.reverse(); assert!(v == [3, 2, 1]);
fn iter(&self) -> Iter<T>
Returns an iterator over the slice.
fn iter_mut(&mut self) -> IterMut<T>
Returns an iterator that allows modifying each value
fn windows(&self, size: usize) -> Windows<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.
Example
Print the adjacent pairs of a slice (i.e. [1,2], [2,3],
[3,4]):
let v = &[1, 2, 3, 4]; for win in v.windows(2) { println!("{:?}", win); }
fn chunks(&self, size: usize) -> Chunks<T>
Returns an iterator over size elements of the slice at a
time. The chunks do not overlap. If size does not divide the
length of the slice, then the last chunk will not have length
size.
Panics
Panics if size is 0.
Example
Print the slice two elements at a time (i.e. [1,2],
[3,4], [5]):
let v = &[1, 2, 3, 4, 5]; for win in v.chunks(2) { println!("{:?}", win); }
fn chunks_mut(&mut self, chunk_size: usize) -> ChunksMut<T>
Returns an iterator over chunk_size elements of the slice at a time.
The chunks are mutable 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.
Panics
Panics if chunk_size is 0.
fn split_at(&self, mid: usize) -> (&[T], &[T])
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
fn main() { let v = [10, 40, 30, 20, 50]; let (v1, v2) = v.split_at(2); assert_eq!([10, 40], v1); assert_eq!([30, 20, 50], v2); }let v = [10, 40, 30, 20, 50]; let (v1, v2) = v.split_at(2); assert_eq!([10, 40], v1); assert_eq!([30, 20, 50], v2);
fn split_at_mut(&mut self, mid: usize) -> (&mut [T], &mut [T])
Divides one &mut 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.
Example
fn main() { let mut v = [1, 2, 3, 4, 5, 6]; // scoped to restrict the lifetime of the borrows { let (left, right) = v.split_at_mut(0); assert!(left == []); assert!(right == [1, 2, 3, 4, 5, 6]); } { let (left, right) = v.split_at_mut(2); assert!(left == [1, 2]); assert!(right == [3, 4, 5, 6]); } { let (left, right) = v.split_at_mut(6); assert!(left == [1, 2, 3, 4, 5, 6]); assert!(right == []); } }let mut v = [1, 2, 3, 4, 5, 6]; // scoped to restrict the lifetime of the borrows { let (left, right) = v.split_at_mut(0); assert!(left == []); assert!(right == [1, 2, 3, 4, 5, 6]); } { let (left, right) = v.split_at_mut(2); assert!(left == [1, 2]); assert!(right == [3, 4, 5, 6]); } { let (left, right) = v.split_at_mut(6); assert!(left == [1, 2, 3, 4, 5, 6]); assert!(right == []); }
fn split<F>(&self, pred: F) -> Split<T, F> where F: FnMut(&T) -> bool
Returns an iterator over subslices separated by elements that match
pred. The matched element is not contained in the subslices.
Examples
Print the slice split by numbers divisible by 3 (i.e. [10, 40],
[20], [50]):
let v = [10, 40, 30, 20, 60, 50]; for group in v.split(|num| *num % 3 == 0) { println!("{:?}", group); }
fn split_mut<F>(&mut self, pred: F) -> SplitMut<T, F> where F: FnMut(&T) -> bool
Returns an iterator over mutable subslices separated by elements that
match pred. The matched element is not contained in the subslices.
fn splitn<F>(&self, n: usize, pred: F) -> SplitN<T, F> where F: FnMut(&T) -> bool
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); }
fn splitn_mut<F>(&mut self, n: usize, pred: F) -> SplitNMut<T, F> where F: FnMut(&T) -> bool
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.
fn rsplitn<F>(&self, n: usize, pred: F) -> RSplitN<T, F> where F: FnMut(&T) -> bool
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. [50], [10, 40, 30, 20]):
let v = [10, 40, 30, 20, 60, 50]; for group in v.rsplitn(2, |num| *num % 3 == 0) { println!("{:?}", group); }
fn rsplitn_mut<F>(&mut self, n: usize, pred: F) -> RSplitNMut<T, F> where F: FnMut(&T) -> bool
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.
fn contains(&self, x: &T) -> bool where T: PartialEq<T>
Returns true if the slice contains an element with the given value.
Examples
fn main() { let v = [10, 40, 30]; assert!(v.contains(&30)); assert!(!v.contains(&50)); }let v = [10, 40, 30]; assert!(v.contains(&30)); assert!(!v.contains(&50));
fn starts_with(&self, needle: &[T]) -> bool where T: PartialEq<T>
Returns true if needle is a prefix of the slice.
Examples
fn main() { let v = [10, 40, 30]; assert!(v.starts_with(&[10])); assert!(v.starts_with(&[10, 40])); assert!(!v.starts_with(&[50])); assert!(!v.starts_with(&[10, 50])); }let v = [10, 40, 30]; assert!(v.starts_with(&[10])); assert!(v.starts_with(&[10, 40])); assert!(!v.starts_with(&[50])); assert!(!v.starts_with(&[10, 50]));
fn ends_with(&self, needle: &[T]) -> bool where T: PartialEq<T>
Returns true if needle is a suffix of the slice.
Examples
fn main() { let v = [10, 40, 30]; assert!(v.ends_with(&[30])); assert!(v.ends_with(&[40, 30])); assert!(!v.ends_with(&[50])); assert!(!v.ends_with(&[50, 30])); }let v = [10, 40, 30]; assert!(v.ends_with(&[30])); assert!(v.ends_with(&[40, 30])); assert!(!v.ends_with(&[50])); assert!(!v.ends_with(&[50, 30]));
fn binary_search(&self, x: &T) -> Result<usize, usize> where T: Ord
Binary search a sorted slice for a given element.
If the value is found then Ok is returned, containing the
index of the matching element; if the value is not found then
Err is returned, containing the index where a matching
element could be inserted while maintaining sorted order.
Example
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, });
fn binary_search_by<F>(&self, f: F) -> Result<usize, usize> where F: FnMut(&T) -> Ordering
Binary search a 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 a matching value is found then returns Ok, containing
the index for the matched element; if no match is found then
Err is returned, containing the index where a matching
element could be inserted while maintaining sorted order.
Example
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, });
fn sort(&mut self) where T: Ord
Sorts the slice, in place.
This is equivalent to self.sort_by(|a, b| a.cmp(b)).
This is a stable sort.
Examples
fn main() { let mut v = [-5, 4, 1, -3, 2]; v.sort(); assert!(v == [-5, -3, 1, 2, 4]); }let mut v = [-5, 4, 1, -3, 2]; v.sort(); assert!(v == [-5, -3, 1, 2, 4]);
fn sort_by_key<B, F>(&mut self, f: F) where B: Ord, F: FnMut(&T) -> B
Sorts the slice, in place, using key to extract a key by which to
order the sort by.
This sort is O(n log n) worst-case and stable, but allocates
approximately 2 * n, where n is the length of self.
This is a stable sort.
Examples
#![feature(slice_sort_by_key)] fn main() { let mut v = [-5i32, 4, 1, -3, 2]; v.sort_by_key(|k| k.abs()); assert!(v == [1, 2, -3, 4, -5]); }#![feature(slice_sort_by_key)] let mut v = [-5i32, 4, 1, -3, 2]; v.sort_by_key(|k| k.abs()); assert!(v == [1, 2, -3, 4, -5]);
fn sort_by<F>(&mut self, compare: F) where F: FnMut(&T, &T) -> Ordering
Sorts the slice, in place, using compare to compare
elements.
This sort is O(n log n) worst-case and stable, but allocates
approximately 2 * n, where n is the length of self.
Examples
fn main() { 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]); }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]);
fn clone_from_slice(&mut self, src: &[T]) -> usize where T: Clone
clone_from_slice #27750)Copies as many elements from src as it can into self (the
shorter of self.len() and src.len()). Returns the number
of elements copied.
Example
#![feature(clone_from_slice)] fn main() { let mut dst = [0, 0, 0]; let src = [1, 2]; assert!(dst.clone_from_slice(&src) == 2); assert!(dst == [1, 2, 0]); let src2 = [3, 4, 5, 6]; assert!(dst.clone_from_slice(&src2) == 3); assert!(dst == [3, 4, 5]); }#![feature(clone_from_slice)] let mut dst = [0, 0, 0]; let src = [1, 2]; assert!(dst.clone_from_slice(&src) == 2); assert!(dst == [1, 2, 0]); let src2 = [3, 4, 5, 6]; assert!(dst.clone_from_slice(&src2) == 3); assert!(dst == [3, 4, 5]);
fn to_vec(&self) -> Vec<T> where T: Clone
Copies self into a new Vec.
fn into_vec(self: Box<[T]>) -> Vec<T>
Converts self into a vector without clones or allocation.