# Struct std::collections::hash_set::Iter 1.0.0 [−] [src]

    pub struct Iter<'a, K: 'a> { /* fields omitted */ }

An iterator over the items of a `HashSet`.

This `struct` is created by the `iter` method on `HashSet`. See its documentation for more.

## Trait Implementations

### `impl<'a, K> Clone for Iter<'a, K>`
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####
ⓘImportant traits for Iter<'a, K>

### Important traits for Iter<'a, K>

`impl<'a, K> Iterator for Iter<'a, K> type Item = &'a K;`
`fn clone(&self) -> Iter<'a, K>`
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Returns a copy of the value. Read more

#### `fn clone_from(&mut self, source: &Self)`
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Performs copy-assignment from `source`. Read more

### `impl<'a, K> Iterator for Iter<'a, K>`
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#### `type Item = &'a K`

The type of the elements being iterated over.

#### `fn next(&mut self) -> Option<&'a K>`
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Advances the iterator and returns the next value. Read more

#### `fn size_hint(&self) -> (usize, Option<usize>)`
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Returns the bounds on the remaining length of the iterator. Read more

#### `fn count(self) -> usize`
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Consumes the iterator, counting the number of iterations and returning it. Read more

#### `fn last(self) -> Option<Self::Item>`
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Consumes the iterator, returning the last element. Read more

#### `fn nth(&mut self, n: usize) -> Option<Self::Item>`
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Returns the `n`th element of the iterator. Read more

####
ⓘImportant traits for StepBy<I>

### Important traits for StepBy<I>

`impl<I> Iterator for StepBy<I> where
I: Iterator, type Item = <I as Iterator>::Item;`
`fn step_by(self, step: usize) -> StepBy<Self>`
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🔬 This is a nightly-only experimental API. (`iterator_step_by` #27741)

unstable replacement of Range::step_by

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

####
ⓘImportant traits for Chain<A, B>

### Important traits for Chain<A, B>

`impl<A, B> Iterator for Chain<A, B> where
A: Iterator,
B: Iterator<Item = <A as Iterator>::Item>, type Item = <A as Iterator>::Item;`
`fn chain<U>(self, other: U) -> Chain<Self, <U as IntoIterator>::IntoIter> where
U: IntoIterator<Item = Self::Item>,`
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Takes two iterators and creates a new iterator over both in sequence. Read more

####
ⓘImportant traits for Zip<A, B>

### Important traits for Zip<A, B>

`impl<A, B> Iterator for Zip<A, B> where
A: Iterator,
B: Iterator, type Item = (<A as Iterator>::Item, <B as Iterator>::Item);`
`fn zip<U>(self, other: U) -> Zip<Self, <U as IntoIterator>::IntoIter> where
U: IntoIterator,`
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'Zips up' two iterators into a single iterator of pairs. Read more

####
ⓘImportant traits for Map<I, F>

### Important traits for Map<I, F>

`impl<B, I, F> Iterator for Map<I, F> where
F: FnMut(<I as Iterator>::Item) -> B,
I: Iterator, type Item = B;`
`fn map<B, F>(self, f: F) -> Map<Self, F> where
F: FnMut(Self::Item) -> B,`
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Takes a closure and creates an iterator which calls that closure on each element. Read more

#### `fn for_each<F>(self, f: F) where
F: FnMut(Self::Item) -> (),`
1.21.0
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Calls a closure on each element of an iterator. Read more

####
ⓘImportant traits for Filter<I, P>

### Important traits for Filter<I, P>

`impl<I, P> Iterator for Filter<I, P> where
I: Iterator,
P: FnMut(&<I as Iterator>::Item) -> bool, type Item = <I as Iterator>::Item;`
`fn filter<P>(self, predicate: P) -> Filter<Self, P> where
P: FnMut(&Self::Item) -> bool,`
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Creates an iterator which uses a closure to determine if an element should be yielded. Read more

####
ⓘImportant traits for FilterMap<I, F>

### Important traits for FilterMap<I, F>

`impl<B, I, F> Iterator for FilterMap<I, F> where
F: FnMut(<I as Iterator>::Item) -> Option<B>,
I: Iterator, type Item = B;`
`fn filter_map<B, F>(self, f: F) -> FilterMap<Self, F> where
F: FnMut(Self::Item) -> Option<B>,`
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Creates an iterator that both filters and maps. Read more

####
ⓘImportant traits for Enumerate<I>

### 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>`
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Creates an iterator which gives the current iteration count as well as the next value. Read more

####
ⓘImportant traits for Peekable<I>

### Important traits for Peekable<I>

`impl<I> Iterator for Peekable<I> where
I: Iterator, type Item = <I as Iterator>::Item;`
`fn peekable(self) -> Peekable<Self>`
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Creates an iterator which can use `peek` to look at the next element of the iterator without consuming it. Read more

####
ⓘImportant traits for SkipWhile<I, P>

### Important traits for SkipWhile<I, P>

`impl<I, P> Iterator for SkipWhile<I, P> where
I: Iterator,
P: FnMut(&<I as Iterator>::Item) -> bool, type Item = <I as Iterator>::Item;`
`fn skip_while<P>(self, predicate: P) -> SkipWhile<Self, P> where
P: FnMut(&Self::Item) -> bool,`
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Creates an iterator that [`skip`]s elements based on a predicate. Read more

####
ⓘImportant traits for TakeWhile<I, P>

### Important traits for TakeWhile<I, P>

`impl<I, P> Iterator for TakeWhile<I, P> where
I: Iterator,
P: FnMut(&<I as Iterator>::Item) -> bool, type Item = <I as Iterator>::Item;`
`fn take_while<P>(self, predicate: P) -> TakeWhile<Self, P> where
P: FnMut(&Self::Item) -> bool,`
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Creates an iterator that yields elements based on a predicate. Read more

####
ⓘImportant traits for Skip<I>

### 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>`
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Creates an iterator that skips the first `n` elements. Read more

####
ⓘImportant traits for Take<I>

### 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>`
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Creates an iterator that yields its first `n` elements. Read more

####
ⓘImportant traits for Scan<I, St, F>

### Important traits for Scan<I, St, F>

`impl<B, I, St, F> Iterator for Scan<I, St, F> where
F: FnMut(&mut St, <I as Iterator>::Item) -> Option<B>,
I: Iterator, type Item = B;`
`fn scan<St, B, F>(self, initial_state: St, f: F) -> Scan<Self, St, F> where
F: FnMut(&mut St, Self::Item) -> Option<B>,`
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An iterator adaptor similar to [`fold`] that holds internal state and produces a new iterator. Read more

####
ⓘImportant traits for FlatMap<I, U, F>

### Important traits for FlatMap<I, U, F>

`impl<I, U, F> Iterator for FlatMap<I, U, F> where
F: FnMut(<I as Iterator>::Item) -> U,
I: Iterator,
U: IntoIterator, type Item = <U as IntoIterator>::Item;`
`fn flat_map<U, F>(self, f: F) -> FlatMap<Self, U, F> where
F: FnMut(Self::Item) -> U,
U: IntoIterator,`
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Creates an iterator that works like map, but flattens nested structure. Read more

####
ⓘImportant traits for Fuse<I>

### 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>`
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Creates an iterator which ends after the first [`None`]. Read more

####
ⓘImportant traits for Inspect<I, F>

### Important traits for Inspect<I, F>

`impl<I, F> Iterator for Inspect<I, F> where
F: FnMut(&<I as Iterator>::Item) -> (),
I: Iterator, type Item = <I as Iterator>::Item;`
`fn inspect<F>(self, f: F) -> Inspect<Self, F> where
F: FnMut(&Self::Item) -> (),`
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Do something with each element of an iterator, passing the value on. Read more

####
ⓘImportant traits for &'a mut I

### Important traits for &'a mut I

`impl<'a, I> Iterator for &'a mut I where
I: Iterator + ?Sized, type Item = <I as Iterator>::Item;impl<'a, R: Read + ?Sized> Read for &'a mut Rimpl<'a, W: Write + ?Sized> Write for &'a mut W`
`fn by_ref(&mut self) -> &mut Self`
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Borrows an iterator, rather than consuming it. Read more

#### `fn collect<B>(self) -> B where
B: FromIterator<Self::Item>,`
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Transforms an iterator into a collection. Read more

#### `fn partition<B, F>(self, f: F) -> (B, B) where
B: Default + Extend<Self::Item>,
F: FnMut(&Self::Item) -> bool,`
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Consumes an iterator, creating two collections from it. Read more

#### `fn try_fold<B, F, R>(&mut self, init: B, f: F) -> R where
F: FnMut(B, Self::Item) -> R,
R: Try<Ok = B>,`
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🔬 This is a nightly-only experimental API. (`iterator_try_fold` #45594)

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

#### `fn fold<B, F>(self, init: B, f: F) -> B where
F: FnMut(B, Self::Item) -> B,`
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An iterator method that applies a function, producing a single, final value. Read more

#### `fn all<F>(&mut self, f: F) -> bool where
F: FnMut(Self::Item) -> bool,`
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Tests if every element of the iterator matches a predicate. Read more

#### `fn any<F>(&mut self, f: F) -> bool where
F: FnMut(Self::Item) -> bool,`
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Tests if any element of the iterator matches a predicate. Read more

#### `fn find<P>(&mut self, predicate: P) -> Option<Self::Item> where
P: FnMut(&Self::Item) -> bool,`
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Searches for an element of an iterator that satisfies a predicate. Read more

#### `fn position<P>(&mut self, predicate: P) -> Option<usize> where
P: FnMut(Self::Item) -> bool,`
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Searches for an element in an iterator, returning its index. Read more

#### `fn rposition<P>(&mut self, predicate: P) -> Option<usize> where
P: FnMut(Self::Item) -> bool,
Self: ExactSizeIterator + DoubleEndedIterator,`
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Searches for an element in an iterator from the right, returning its index. Read more

#### `fn max(self) -> Option<Self::Item> where
Self::Item: Ord,`
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Returns the maximum element of an iterator. Read more

#### `fn min(self) -> Option<Self::Item> where
Self::Item: Ord,`
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Returns the minimum element of an iterator. Read more

#### `fn max_by_key<B, F>(self, f: F) -> Option<Self::Item> where
B: Ord,
F: FnMut(&Self::Item) -> B,`
1.6.0
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Returns the element that gives the maximum value from the specified function. Read more

#### `fn max_by<F>(self, compare: F) -> Option<Self::Item> where
F: FnMut(&Self::Item, &Self::Item) -> Ordering,`
1.15.0
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Returns the element that gives the maximum value with respect to the specified comparison function. Read more

#### `fn min_by_key<B, F>(self, f: F) -> Option<Self::Item> where
B: Ord,
F: FnMut(&Self::Item) -> B,`
1.6.0
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Returns the element that gives the minimum value from the specified function. Read more

#### `fn min_by<F>(self, compare: F) -> Option<Self::Item> where
F: FnMut(&Self::Item, &Self::Item) -> Ordering,`
1.15.0
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Returns the element that gives the minimum value with respect to the specified comparison function. Read more

####
ⓘImportant traits for Rev<I>

### 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: DoubleEndedIterator,`
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Reverses an iterator's direction. Read more

#### `fn unzip<A, B, FromA, FromB>(self) -> (FromA, FromB) where
FromA: Default + Extend<A>,
FromB: Default + Extend<B>,
Self: Iterator<Item = (A, B)>,`
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Converts an iterator of pairs into a pair of containers. Read more

####
ⓘImportant traits for Cloned<I>

### Important traits for Cloned<I>

`impl<'a, I, T> Iterator for Cloned<I> where
I: Iterator<Item = &'a T>,
T: 'a + Clone, type Item = T;`
`fn cloned<'a, T>(self) -> Cloned<Self> where
Self: Iterator<Item = &'a T>,
T: 'a + Clone,`
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Creates an iterator which [`clone`]s all of its elements. Read more

####
ⓘImportant traits for Cycle<I>

### 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: Clone,`
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Repeats an iterator endlessly. Read more

#### `fn sum<S>(self) -> S where
S: Sum<Self::Item>,`
1.11.0
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Sums the elements of an iterator. Read more

#### `fn product<P>(self) -> P where
P: Product<Self::Item>,`
1.11.0
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Iterates over the entire iterator, multiplying all the elements Read more

#### `fn cmp<I>(self, other: I) -> Ordering where
I: IntoIterator<Item = Self::Item>,
Self::Item: Ord,`
1.5.0
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Lexicographically compares the elements of this `Iterator` with those of another. Read more

#### `fn partial_cmp<I>(self, other: I) -> Option<Ordering> where
I: IntoIterator,
Self::Item: PartialOrd<<I as IntoIterator>::Item>,`
1.5.0
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Lexicographically compares the elements of this `Iterator` with those of another. Read more

#### `fn eq<I>(self, other: I) -> bool where
I: IntoIterator,
Self::Item: PartialEq<<I as IntoIterator>::Item>,`
1.5.0
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Determines if the elements of this `Iterator` are equal to those of another. Read more

#### `fn ne<I>(self, other: I) -> bool where
I: IntoIterator,
Self::Item: PartialEq<<I as IntoIterator>::Item>,`
1.5.0
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Determines if the elements of this `Iterator` are unequal to those of another. Read more

#### `fn lt<I>(self, other: I) -> bool where
I: IntoIterator,
Self::Item: PartialOrd<<I as IntoIterator>::Item>,`
1.5.0
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Determines if the elements of this `Iterator` are lexicographically less than those of another. Read more

#### `fn le<I>(self, other: I) -> bool where
I: IntoIterator,
Self::Item: PartialOrd<<I as IntoIterator>::Item>,`
1.5.0
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Determines if the elements of this `Iterator` are lexicographically less or equal to those of another. Read more

#### `fn gt<I>(self, other: I) -> bool where
I: IntoIterator,
Self::Item: PartialOrd<<I as IntoIterator>::Item>,`
1.5.0
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Determines if the elements of this `Iterator` are lexicographically greater than those of another. Read more

#### `fn ge<I>(self, other: I) -> bool where
I: IntoIterator,
Self::Item: PartialOrd<<I as IntoIterator>::Item>,`
1.5.0
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Determines if the elements of this `Iterator` are lexicographically greater than or equal to those of another. Read more

### `impl<'a, K> ExactSizeIterator for Iter<'a, K>`
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#### `fn len(&self) -> usize`
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Returns the exact number of times the iterator will iterate. Read more

#### `fn is_empty(&self) -> bool`
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🔬 This is a nightly-only experimental API. (`exact_size_is_empty` #35428)

Returns whether the iterator is empty. Read more

### `impl<'a, K> FusedIterator for Iter<'a, K>`
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### `impl<'a, K: Debug> Debug for Iter<'a, K>`
1.16.0
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#### `fn fmt(&self, f: &mut Formatter) -> Result`
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Formats the value using the given formatter. Read more

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