Struct core::slice::Iter

pub struct Iter<'a, T: 'a> { /* fields omitted */ }

Immutable slice iterator

This struct is created by the iter method on slices.

Examples

Basic usage:

// First, we declare a type which has `iter` method to get the `Iter` struct (&[usize here]):
let slice = &[1, 2, 3];

// Then, we iterate over it:
for element in slice.iter() {
    println!("{}", element);
}

Methods

impl<'a, T> Iter<'a, T>

pub fn as_slice(&self) -> &'a [T]

Views the underlying data as a subslice of the original data.

This has the same lifetime as the original slice, and so the iterator can continue to be used while this exists.

Examples

Basic usage:

// First, we declare a type which has the `iter` method to get the `Iter`
// struct (&[usize here]):
let slice = &[1, 2, 3];

// Then, we get the iterator:
let mut iter = slice.iter();
// So if we print what `as_slice` method returns here, we have "[1, 2, 3]":
println!("{:?}", iter.as_slice());

// Next, we move to the second element of the slice:
iter.next();
// Now `as_slice` returns "[2, 3]":
println!("{:?}", iter.as_slice());

Trait Implementations

impl<T: Sync, '_> Send for Iter<'_, T>

impl<T: Sync, '_> Sync for Iter<'_, T>

impl<T, '_> Clone for Iter<'_, T>

fn clone(&self) -> Self

Returns a copy of the value.

fn clone_from(&mut self, source: &Self)

Performs copy-assignment from source.

impl<T, '_> AsRef<[T]> for Iter<'_, T>

fn as_ref(&self) -> &[T]

Performs the conversion.

impl<'a, T> Iterator for Iter<'a, T>

type Item = &'a T

The type of the elements being iterated over.

fn next(&mut self) -> Option<&'a T>

Advances the iterator and returns the next value.

fn size_hint(&self) -> (usize, Option<usize>)

Returns the bounds on the remaining length of the iterator.

fn count(self) -> usize

Consumes the iterator, counting the number of iterations and returning it.

fn nth(&mut self, n: usize) -> Option<&'a T>

Returns the nth element of the iterator.

fn last(self) -> Option<&'a T>

Consumes the iterator, returning the last element.

fn try_fold<B, F, R>(&mut self, init: B, f: F) -> R where
    Self: Sized,
    F: FnMut(B, Self::Item) -> R,
    R: Try<Ok = B>, 

An iterator method that applies a function as long as it returns successfully, producing a single, final value.

fn fold<Acc, Fold>(self, init: Acc, f: Fold) -> Acc where
    Fold: FnMut(Acc, Self::Item) -> Acc, 

An iterator method that applies a function, producing a single, final value.

fn position<P>(&mut self, predicate: P) -> Option<usize> where
    Self: Sized,
    P: FnMut(Self::Item) -> bool, 

Searches for an element in an iterator, returning its index.

fn rposition<P>(&mut self, predicate: P) -> Option<usize> where
    P: FnMut(Self::Item) -> bool,
    Self: Sized + ExactSizeIterator + DoubleEndedIterator, 

Searches for an element in an iterator from the right, returning its index.

fn is_sorted_by<F>(self, compare: F) -> bool where
    Self: Sized,
    F: FnMut(&Self::Item, &Self::Item) -> Option<Ordering>, 

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

new API

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

Important traits for StepBy<I>

impl<I> Iterator for StepBy<I> where
    I: Iterator,  type Item = I::Item;

fn step_by(self, step: usize) -> StepBy<Self> where
    Self: Sized, 

Creates an iterator starting at the same point, but stepping by the given amount at each iteration.

Important traits for Chain<A, B>

impl<A, B> Iterator for Chain<A, B> where
    A: Iterator,
    B: Iterator<Item = A::Item>,  type Item = A::Item;

fn chain<U>(self, other: U) -> Chain<Self, U::IntoIter> where
    Self: Sized,
    U: IntoIterator<Item = Self::Item>, 

Takes two iterators and creates a new iterator over both in sequence.

Important traits for Zip<A, B>

impl<A, B> Iterator for Zip<A, B> where
    A: Iterator,
    B: Iterator,  type Item = (A::Item, B::Item);

fn zip<U>(self, other: U) -> Zip<Self, U::IntoIter> where
    Self: Sized,
    U: IntoIterator, 

'Zips up' two iterators into a single iterator of pairs.

Important traits for Map<I, F>

impl<B, I: Iterator, F> Iterator for Map<I, F> where
    F: FnMut(I::Item) -> B,  type Item = B;

fn map<B, F>(self, f: F) -> Map<Self, F> where
    Self: Sized,
    F: FnMut(Self::Item) -> B, 

Takes a closure and creates an iterator which calls that closure on each element.

fn for_each<F>(self, f: F) where
    Self: Sized,
    F: FnMut(Self::Item), 

Calls a closure on each element of an iterator.

Important traits for Filter<I, P>

impl<I: Iterator, P> Iterator for Filter<I, P> where
    P: FnMut(&I::Item) -> bool,  type Item = I::Item;

fn filter<P>(self, predicate: P) -> Filter<Self, P> where
    Self: Sized,
    P: FnMut(&Self::Item) -> bool, 

Creates an iterator which uses a closure to determine if an element should be yielded.

Important traits for FilterMap<I, F>

impl<B, I: Iterator, F> Iterator for FilterMap<I, F> where
    F: FnMut(I::Item) -> Option<B>,  type Item = B;

fn filter_map<B, F>(self, f: F) -> FilterMap<Self, F> where
    Self: Sized,
    F: FnMut(Self::Item) -> Option<B>, 

Creates an iterator that both filters and maps.

Important traits for Enumerate<I>

impl<I> Iterator for Enumerate<I> where
    I: Iterator,  type Item = (usize, <I as Iterator>::Item);

fn enumerate(self) -> Enumerate<Self> where
    Self: Sized, 

Creates an iterator which gives the current iteration count as well as the next value.

Important traits for Peekable<I>

impl<I: Iterator> Iterator for Peekable<I> type Item = I::Item;

fn peekable(self) -> Peekable<Self> where
    Self: Sized, 

Creates an iterator which can use peek to look at the next element of the iterator without consuming it.

Important traits for SkipWhile<I, P>

impl<I: Iterator, P> Iterator for SkipWhile<I, P> where
    P: FnMut(&I::Item) -> bool,  type Item = I::Item;

fn skip_while<P>(self, predicate: P) -> SkipWhile<Self, P> where
    Self: Sized,
    P: FnMut(&Self::Item) -> bool, 

Creates an iterator that [skip]s elements based on a predicate.

Important traits for TakeWhile<I, P>

impl<I: Iterator, P> Iterator for TakeWhile<I, P> where
    P: FnMut(&I::Item) -> bool,  type Item = I::Item;

fn take_while<P>(self, predicate: P) -> TakeWhile<Self, P> where
    Self: Sized,
    P: FnMut(&Self::Item) -> bool, 

Creates an iterator that yields elements based on a predicate.

Important traits for Skip<I>

impl<I> Iterator for Skip<I> where
    I: Iterator,  type Item = <I as Iterator>::Item;

fn skip(self, n: usize) -> Skip<Self> where
    Self: Sized, 

Creates an iterator that skips the first n elements.

Important traits for Take<I>

impl<I> Iterator for Take<I> where
    I: Iterator,  type Item = <I as Iterator>::Item;

fn take(self, n: usize) -> Take<Self> where
    Self: Sized, 

Creates an iterator that yields its first n elements.

Important traits for Scan<I, St, F>

impl<B, I, St, F> Iterator for Scan<I, St, F> where
    I: Iterator,
    F: FnMut(&mut St, I::Item) -> Option<B>,  type Item = B;

fn scan<St, B, F>(self, initial_state: St, f: F) -> Scan<Self, St, F> where
    Self: Sized,
    F: FnMut(&mut St, Self::Item) -> Option<B>, 

An iterator adaptor similar to [fold] that holds internal state and produces a new iterator.

Important traits for FlatMap<I, U, F>

impl<I: Iterator, U: IntoIterator, F> Iterator for FlatMap<I, U, F> where
    F: FnMut(I::Item) -> U,  type Item = U::Item;

fn flat_map<U, F>(self, f: F) -> FlatMap<Self, U, F> where
    Self: Sized,
    U: IntoIterator,
    F: FnMut(Self::Item) -> U, 

Creates an iterator that works like map, but flattens nested structure.

Important traits for Flatten<I>

impl<I, U> Iterator for Flatten<I> where
    I: Iterator,
    U: Iterator,
    I::Item: IntoIterator<IntoIter = U, Item = U::Item>,  type Item = U::Item;

fn flatten(self) -> Flatten<Self> where
    Self: Sized,
    Self::Item: IntoIterator, 

Creates an iterator that flattens nested structure.

Important traits for Fuse<I>

impl<I> Iterator for Fuse<I> where
    I: Iterator,  type Item = <I as Iterator>::Item;impl<I> Iterator for Fuse<I> where
    I: FusedIterator, 

fn fuse(self) -> Fuse<Self> where
    Self: Sized, 

Creates an iterator which ends after the first [None].

Important traits for Inspect<I, F>

impl<I: Iterator, F> Iterator for Inspect<I, F> where
    F: FnMut(&I::Item),  type Item = I::Item;

fn inspect<F>(self, f: F) -> Inspect<Self, F> where
    Self: Sized,
    F: FnMut(&Self::Item), 

Do something with each element of an iterator, passing the value on.

fn by_ref(&mut self) -> &mut Self where
    Self: Sized, 

Borrows an iterator, rather than consuming it.

#[must_use = "if you really need to exhaust the iterator, consider `.for_each(drop)` instead"]

fn collect<B: FromIterator<Self::Item>>(self) -> B where
    Self: Sized, 

Transforms an iterator into a collection.

fn partition<B, F>(self, f: F) -> (B, B) where
    Self: Sized,
    B: Default + Extend<Self::Item>,
    F: FnMut(&Self::Item) -> bool, 

Consumes an iterator, creating two collections from it.

fn try_for_each<F, R>(&mut self, f: F) -> R where
    Self: Sized,
    F: FnMut(Self::Item) -> R,
    R: Try<Ok = ()>, 

An iterator method that applies a fallible function to each item in the iterator, stopping at the first error and returning that error.

fn all<F>(&mut self, f: F) -> bool where
    Self: Sized,
    F: FnMut(Self::Item) -> bool, 

Tests if every element of the iterator matches a predicate.

fn any<F>(&mut self, f: F) -> bool where
    Self: Sized,
    F: FnMut(Self::Item) -> bool, 

Tests if any element of the iterator matches a predicate.

fn find<P>(&mut self, predicate: P) -> Option<Self::Item> where
    Self: Sized,
    P: FnMut(&Self::Item) -> bool, 

Searches for an element of an iterator that satisfies a predicate.

fn find_map<B, F>(&mut self, f: F) -> Option<B> where
    Self: Sized,
    F: FnMut(Self::Item) -> Option<B>, 

Applies function to the elements of iterator and returns the first non-none result.

fn max(self) -> Option<Self::Item> where
    Self: Sized,
    Self::Item: Ord, 

Returns the maximum element of an iterator.

fn min(self) -> Option<Self::Item> where
    Self: Sized,
    Self::Item: Ord, 

Returns the minimum element of an iterator.

fn max_by_key<B: Ord, F>(self, f: F) -> Option<Self::Item> where
    Self: Sized,
    F: FnMut(&Self::Item) -> B, 

Returns the element that gives the maximum value from the specified function.

fn max_by<F>(self, compare: F) -> Option<Self::Item> where
    Self: Sized,
    F: FnMut(&Self::Item, &Self::Item) -> Ordering, 

Returns the element that gives the maximum value with respect to the specified comparison function.

fn min_by_key<B: Ord, F>(self, f: F) -> Option<Self::Item> where
    Self: Sized,
    F: FnMut(&Self::Item) -> B, 

Returns the element that gives the minimum value from the specified function.

fn min_by<F>(self, compare: F) -> Option<Self::Item> where
    Self: Sized,
    F: FnMut(&Self::Item, &Self::Item) -> Ordering, 

Returns the element that gives the minimum value with respect to the specified comparison function.

Important traits for Rev<I>

impl<I> Iterator for Rev<I> where
    I: DoubleEndedIterator,  type Item = <I as Iterator>::Item;

fn rev(self) -> Rev<Self> where
    Self: Sized + DoubleEndedIterator, 

Reverses an iterator's direction.

fn unzip<A, B, FromA, FromB>(self) -> (FromA, FromB) where
    FromA: Default + Extend<A>,
    FromB: Default + Extend<B>,
    Self: Sized + Iterator<Item = (A, B)>, 

Converts an iterator of pairs into a pair of containers.

Important traits for Copied<I>

impl<'a, I, T: 'a> Iterator for Copied<I> where
    I: Iterator<Item = &'a T>,
    T: Copy,  type Item = T;

fn copied<'a, T: 'a>(self) -> Copied<Self> where
    Self: Sized + Iterator<Item = &'a T>,
    T: Copy, 

🔬 This is a nightly-only experimental API. (iter_copied #57127)

Creates an iterator which copies all of its elements.

Important traits for Cloned<I>

impl<'a, I, T: 'a> Iterator for Cloned<I> where
    I: Iterator<Item = &'a T>,
    T: Clone,  type Item = T;

fn cloned<'a, T: 'a>(self) -> Cloned<Self> where
    Self: Sized + Iterator<Item = &'a T>,
    T: Clone, 

Creates an iterator which [clone]s all of its elements.

Important traits for Cycle<I>

impl<I> Iterator for Cycle<I> where
    I: Clone + Iterator,  type Item = <I as Iterator>::Item;

fn cycle(self) -> Cycle<Self> where
    Self: Sized + Clone, 

Repeats an iterator endlessly.

fn sum<S>(self) -> S where
    Self: Sized,
    S: Sum<Self::Item>, 

Sums the elements of an iterator.

fn product<P>(self) -> P where
    Self: Sized,
    P: Product<Self::Item>, 

Iterates over the entire iterator, multiplying all the elements

fn cmp<I>(self, other: I) -> Ordering where
    I: IntoIterator<Item = Self::Item>,
    Self::Item: Ord,
    Self: Sized, 

Lexicographically compares the elements of this Iterator with those of another.

fn partial_cmp<I>(self, other: I) -> Option<Ordering> where
    I: IntoIterator,
    Self::Item: PartialOrd<I::Item>,
    Self: Sized, 

Lexicographically compares the elements of this Iterator with those of another.

fn eq<I>(self, other: I) -> bool where
    I: IntoIterator,
    Self::Item: PartialEq<I::Item>,
    Self: Sized, 

Determines if the elements of this Iterator are equal to those of another.

fn ne<I>(self, other: I) -> bool where
    I: IntoIterator,
    Self::Item: PartialEq<I::Item>,
    Self: Sized, 

Determines if the elements of this Iterator are unequal to those of another.

fn lt<I>(self, other: I) -> bool where
    I: IntoIterator,
    Self::Item: PartialOrd<I::Item>,
    Self: Sized, 

Determines if the elements of this Iterator are lexicographically less than those of another.

fn le<I>(self, other: I) -> bool where
    I: IntoIterator,
    Self::Item: PartialOrd<I::Item>,
    Self: Sized, 

Determines if the elements of this Iterator are lexicographically less or equal to those of another.

fn gt<I>(self, other: I) -> bool where
    I: IntoIterator,
    Self::Item: PartialOrd<I::Item>,
    Self: Sized, 

Determines if the elements of this Iterator are lexicographically greater than those of another.

fn ge<I>(self, other: I) -> bool where
    I: IntoIterator,
    Self::Item: PartialOrd<I::Item>,
    Self: Sized, 

Determines if the elements of this Iterator are lexicographically greater than or equal to those of another.

fn is_sorted(self) -> bool where
    Self: Sized,
    Self::Item: PartialOrd, 

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

new API

Checks if the elements of this iterator are sorted.

fn is_sorted_by_key<F, K>(self, f: F) -> bool where
    Self: Sized,
    F: FnMut(&Self::Item) -> K,
    K: PartialOrd, 

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

new API

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

impl<'a, T> DoubleEndedIterator for Iter<'a, T>

fn next_back(&mut self) -> Option<&'a T>

Removes and returns an element from the end of the iterator.

fn try_rfold<B, F, R>(&mut self, init: B, f: F) -> R where
    Self: Sized,
    F: FnMut(B, Self::Item) -> R,
    R: Try<Ok = B>, 

This is the reverse version of [try_fold()]: it takes elements starting from the back of the iterator.

fn rfold<Acc, Fold>(self, init: Acc, f: Fold) -> Acc where
    Fold: FnMut(Acc, Self::Item) -> Acc, 

An iterator method that reduces the iterator's elements to a single, final value, starting from the back.

fn nth_back(&mut self, n: usize) -> Option<Self::Item>

🔬 This is a nightly-only experimental API. (iter_nth_back #56995)

Returns the nth element from the end of the iterator.

fn rfind<P>(&mut self, predicate: P) -> Option<Self::Item> where
    Self: Sized,
    P: FnMut(&Self::Item) -> bool, 

Searches for an element of an iterator from the back that satisfies a predicate.

impl<T, '_> ExactSizeIterator for Iter<'_, T>

fn len(&self) -> usize

Returns the exact number of times the iterator will iterate.

fn is_empty(&self) -> bool

🔬 This is a nightly-only experimental API. (exact_size_is_empty #35428)

Returns true if the iterator is empty.

impl<T, '_> FusedIterator for Iter<'_, T>

impl<T, '_> TrustedLen for Iter<'_, T>

impl<T: Debug, '_> Debug for Iter<'_, T>

fn fmt(&self, f: &mut Formatter) -> Result

Formats the value using the given formatter.