std::iter::IntoIterator - Rust
Description: API documentation for the Rust `IntoIterator` trait in crate `std`.
Keywords: rust, rustlang, rust-lang, IntoIterator

# 1.0.0[−][src]Trait std::iter::IntoIterator

    pub trait IntoIterator {
        type Item;
        type IntoIter: Iterator;
    #[lang = "into_iter"]    pub fn into_iter(self) -> Self::IntoIter;
    }

Conversion into an `Iterator`.

By implementing `IntoIterator` for a type, you define how it will be converted to an iterator. This is common for types which describe a collection of some kind.

One benefit of implementing `IntoIterator` is that your type will work with Rust's `for` loop syntax.

See also: `FromIterator`.

# Examples

Basic usage:

    let v = vec![1, 2, 3];
    let mut iter = v.into_iter();

    assert_eq!(Some(1), iter.next());
    assert_eq!(Some(2), iter.next());
    assert_eq!(Some(3), iter.next());
    assert_eq!(None, iter.next());

Run

Implementing `IntoIterator` for your type:

    // A sample collection, that's just a wrapper over Vec<T>
    #[derive(Debug)]
    struct MyCollection(Vec<i32>);

    // Let's give it some methods so we can create one and add things
    // to it.
    impl MyCollection {
        fn new() -> MyCollection {
            MyCollection(Vec::new())
        }

        fn add(&mut self, elem: i32) {
            self.0.push(elem);
        }
    }

    // and we'll implement IntoIterator
    impl IntoIterator for MyCollection {
        type Item = i32;
        type IntoIter = std::vec::IntoIter<Self::Item>;

        fn into_iter(self) -> Self::IntoIter {
            self.0.into_iter()
        }
    }

    // Now we can make a new collection...
    let mut c = MyCollection::new();

    // ... add some stuff to it ...
    c.add(0);
    c.add(1);
    c.add(2);

    // ... and then turn it into an Iterator:
    for (i, n) in c.into_iter().enumerate() {
        assert_eq!(i as i32, n);
    }

Run

It is common to use `IntoIterator` as a trait bound. This allows the input collection type to change, so long as it is still an iterator. Additional bounds can be specified by restricting on `Item`:

    fn collect_as_strings<T>(collection: T) -> Vec<String>
    where
        T: IntoIterator,
        T::Item: std::fmt::Debug,
    {
        collection
            .into_iter()
            .map(|item| format!("{:?}", item))
            .collect()
    }

Run

## Associated Types

### `type Item`[src]

The type of the elements being iterated over.

### `type IntoIter: Iterator`[src]

Which kind of iterator are we turning this into?

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## Required methods

### `#[lang = "into_iter"]pub fn into_iter(self) -> Self::IntoIter`[src]

Creates an iterator from a value.

See the module-level documentation for more.

# Examples

Basic usage:

    let v = vec![1, 2, 3];
    let mut iter = v.into_iter();

    assert_eq!(Some(1), iter.next());
    assert_eq!(Some(2), iter.next());
    assert_eq!(Some(3), iter.next());
    assert_eq!(None, iter.next());

Run
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## Implementors

### `impl<'a> IntoIterator for &'a UnixListener`[src]

This is supported on Unix only.

#### `type Item = Result<UnixStream>`

#### `type IntoIter = Incoming<'a>`

#### `fn into_iter(self) -> Incoming<'a>ⓘ

### Notable traits for Incoming<'a>

`impl<'a> Iterator for Incoming<'a> type Item = Result<UnixStream>;`
`[src]

### `impl<'a> IntoIterator for &'a Path`[src]

#### `type Item = &'a OsStr`

#### `type IntoIter = Iter<'a>`

#### `fn into_iter(self) -> Iter<'a>ⓘ

### Notable traits for Iter<'a>

`impl<'a> Iterator for Iter<'a> type Item = &'a OsStr;`
`[src]

### `impl<'a> IntoIterator for &'a PathBuf`[src]

#### `type Item = &'a OsStr`

#### `type IntoIter = Iter<'a>`

#### `fn into_iter(self) -> Iter<'a>ⓘ

### Notable traits for Iter<'a>

`impl<'a> Iterator for Iter<'a> type Item = &'a OsStr;`
`[src]

### `impl<'a, K, V> IntoIterator for &'a BTreeMap<K, V>`[src]

#### `type Item = (&'a K, &'a V)`

#### `type IntoIter = Iter<'a, K, V>`

#### `pub fn into_iter(self) -> Iter<'a, K, V>ⓘ

### Notable traits for Iter<'a, K, V>

`impl<'a, K, V> Iterator for Iter<'a, K, V> where
K: 'a,
V: 'a, type Item = (&'a K, &'a V);`
`[src]

### `impl<'a, K, V> IntoIterator for &'a mut BTreeMap<K, V>`[src]

#### `type Item = (&'a K, &'a mut V)`

#### `type IntoIter = IterMut<'a, K, V>`

#### `pub fn into_iter(self) -> IterMut<'a, K, V>ⓘ

### Notable traits for IterMut<'a, K, V>

`impl<'a, K, V> Iterator for IterMut<'a, K, V> where
K: 'a,
V: 'a, type Item = (&'a K, &'a mut V);`
`[src]

### `impl<'a, K, V, S> IntoIterator for &'a HashMap<K, V, S>`[src]

#### `type Item = (&'a K, &'a V)`

#### `type IntoIter = Iter<'a, K, V>`

#### `fn into_iter(self) -> Iter<'a, K, V>ⓘ

### Notable traits for Iter<'a, K, V>

`impl<'a, K, V> Iterator for Iter<'a, K, V> type Item = (&'a K, &'a V);`
`[src]

### `impl<'a, K, V, S> IntoIterator for &'a mut HashMap<K, V, S>`[src]

#### `type Item = (&'a K, &'a mut V)`

#### `type IntoIter = IterMut<'a, K, V>`

#### `fn into_iter(self) -> IterMut<'a, K, V>ⓘ

### Notable traits for IterMut<'a, K, V>

`impl<'a, K, V> Iterator for IterMut<'a, K, V> type Item = (&'a K, &'a mut V);`
`[src]

### `impl<'a, T> IntoIterator for &'a Option<T>`[src]

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

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

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

### Notable traits for Iter<'a, A>

`impl<'a, A> Iterator for Iter<'a, A> type Item = &'a A;`
`[src]

### `impl<'a, T> IntoIterator for &'a BTreeSet<T>`[src]

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

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

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

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

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

### `impl<'a, T> IntoIterator for &'a BinaryHeap<T>`[src]

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

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

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

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

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

### `impl<'a, T> IntoIterator for &'a LinkedList<T>`[src]

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

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

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

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

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

### `impl<'a, T> IntoIterator for &'a VecDeque<T>`[src]

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

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

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

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

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

### `impl<'a, T> IntoIterator for &'a Receiver<T>`[src]

#### `type Item = T`

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

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

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

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

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

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

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

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

### Notable traits for IterMut<'a, A>

`impl<'a, A> Iterator for IterMut<'a, A> type Item = &'a mut A;`
`[src]

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

### `impl<'a, T, A> IntoIterator for &'a Vec<T, A> where
A: Allocator,` [src]

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

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

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

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

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

### `impl<'a, T, A> IntoIterator for &'a mut Vec<T, A> where
A: Allocator,` [src]

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

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

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

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

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

### `impl<'a, T, E> IntoIterator for &'a Result<T, E>`[src]

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

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

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

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

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

### `impl<'a, T, E> IntoIterator for &'a mut Result<T, E>`[src]

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

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

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

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

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

### `impl<'a, T, S> IntoIterator for &'a HashSet<T, S>`[src]

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

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

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

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

`impl<'a, K> Iterator for Iter<'a, K> type Item = &'a K;`
`[src]

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

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

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

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

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

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

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

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

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

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

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

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

### `impl<I> IntoIterator for I where
I: Iterator,` [src]

#### `type Item = <I as Iterator>::Item`

#### `type IntoIter = I`

#### `pub fn into_iter(self) -> I`[src]

### `impl<K, V> IntoIterator for BTreeMap<K, V>`[src]

#### `type Item = (K, V)`

#### `type IntoIter = IntoIter<K, V>`

#### `pub fn into_iter(self) -> IntoIter<K, V>ⓘ

### Notable traits for IntoIter<K, V>

`impl<K, V> Iterator for IntoIter<K, V> type Item = (K, V);`
`[src]

### `impl<K, V, S> IntoIterator for HashMap<K, V, S>`[src]

#### `type Item = (K, V)`

#### `type IntoIter = IntoIter<K, V>`

#### `fn into_iter(self) -> IntoIter<K, V>ⓘ

### Notable traits for IntoIter<K, V>

`impl<K, V> Iterator for IntoIter<K, V> type Item = (K, V);`
`[src]

Creates a consuming iterator, that is, one that moves each key-value pair out of the map in arbitrary order. The map cannot be used after calling this.

# Examples

    use std::collections::HashMap;

    let mut map = HashMap::new();
    map.insert("a", 1);
    map.insert("b", 2);
    map.insert("c", 3);

    // Not possible with .iter()
    let vec: Vec<(&str, i32)> = map.into_iter().collect();

Run

### `impl<T> IntoIterator for Option<T>`[src]

#### `type Item = T`

#### `type IntoIter = IntoIter<T>`

#### `pub fn into_iter(self) -> IntoIter<T>ⓘ

### Notable traits for IntoIter<A>

`impl<A> Iterator for IntoIter<A> type Item = A;`
`[src]

Returns a consuming iterator over the possibly contained value.

# Examples

    let x = Some("string");
    let v: Vec<&str> = x.into_iter().collect();
    assert_eq!(v, ["string"]);

    let x = None;
    let v: Vec<&str> = x.into_iter().collect();
    assert!(v.is_empty());

Run

### `impl<T> IntoIterator for BTreeSet<T>`[src]

#### `type Item = T`

#### `type IntoIter = IntoIter<T>`

#### `pub fn into_iter(self) -> IntoIter<T>ⓘ

### Notable traits for IntoIter<T>

`impl<T> Iterator for IntoIter<T> type Item = T;`
`[src]

Gets an iterator for moving out the `BTreeSet`'s contents.

# Examples

    use std::collections::BTreeSet;

    let set: BTreeSet<usize> = [1, 2, 3, 4].iter().cloned().collect();

    let v: Vec<_> = set.into_iter().collect();
    assert_eq!(v, [1, 2, 3, 4]);

Run

### `impl<T> IntoIterator for BinaryHeap<T>`[src]

#### `type Item = T`

#### `type IntoIter = IntoIter<T>`

#### `pub fn into_iter(self) -> IntoIter<T>ⓘ

### Notable traits for IntoIter<T>

`impl<T> Iterator for IntoIter<T> type Item = T;`
`[src]

Creates a consuming iterator, that is, one that moves each value out of the binary heap in arbitrary order. The binary heap cannot be used after calling this.

# Examples

Basic usage:

    use std::collections::BinaryHeap;
    let heap = BinaryHeap::from(vec![1, 2, 3, 4]);

    // Print 1, 2, 3, 4 in arbitrary order
    for x in heap.into_iter() {
        // x has type i32, not &i32
        println!("{}", x);
    }

Run

### `impl<T> IntoIterator for LinkedList<T>`[src]

#### `type Item = T`

#### `type IntoIter = IntoIter<T>`

#### `pub fn into_iter(self) -> IntoIter<T>ⓘ

### Notable traits for IntoIter<T>

`impl<T> Iterator for IntoIter<T> type Item = T;`
`[src]

Consumes the list into an iterator yielding elements by value.

### `impl<T> IntoIterator for VecDeque<T>`[src]

#### `type Item = T`

#### `type IntoIter = IntoIter<T>`

#### `pub fn into_iter(self) -> IntoIter<T>ⓘ

### Notable traits for IntoIter<T>

`impl<T> Iterator for IntoIter<T> type Item = T;`
`[src]

Consumes the `VecDeque` into a front-to-back iterator yielding elements by value.

### `impl<T> IntoIterator for Receiver<T>`[src]

#### `type Item = T`

#### `type IntoIter = IntoIter<T>`

#### `fn into_iter(self) -> IntoIter<T>ⓘ

### Notable traits for IntoIter<T>

`impl<T> Iterator for IntoIter<T> type Item = T;`
`[src]

### `impl<T, A> IntoIterator for Vec<T, A> where
A: Allocator,` [src]

#### `type Item = T`

#### `type IntoIter = IntoIter<T, A>`

#### `pub fn into_iter(self) -> IntoIter<T, A>ⓘ

### Notable traits for IntoIter<T, A>

`impl<T, A> Iterator for IntoIter<T, A> where
A: Allocator, type Item = T;`
`[src]

Creates a consuming iterator, that is, one that moves each value out of the vector (from start to end). The vector cannot be used after calling this.

# Examples

    let v = vec!["a".to_string(), "b".to_string()];
    for s in v.into_iter() {
        // s has type String, not &String
        println!("{}", s);
    }

Run

### `impl<T, E> IntoIterator for Result<T, E>`[src]

#### `type Item = T`

#### `type IntoIter = IntoIter<T>`

#### `pub fn into_iter(self) -> IntoIter<T>ⓘ

### Notable traits for IntoIter<T>

`impl<T> Iterator for IntoIter<T> type Item = T;`
`[src]

Returns a consuming iterator over the possibly contained value.

The iterator yields one value if the result is `Result::Ok`, otherwise none.

# Examples

Basic usage:

    let x: Result<u32, &str> = Ok(5);
    let v: Vec<u32> = x.into_iter().collect();
    assert_eq!(v, [5]);

    let x: Result<u32, &str> = Err("nothing!");
    let v: Vec<u32> = x.into_iter().collect();
    assert_eq!(v, []);

Run

### `impl<T, S> IntoIterator for HashSet<T, S>`[src]

#### `type Item = T`

#### `type IntoIter = IntoIter<T>`

#### `fn into_iter(self) -> IntoIter<T>ⓘ

### Notable traits for IntoIter<K>

`impl<K> Iterator for IntoIter<K> type Item = K;`
`[src]

Creates a consuming iterator, that is, one that moves each value out of the set in arbitrary order. The set cannot be used after calling this.

# Examples

    use std::collections::HashSet;
    let mut set = HashSet::new();
    set.insert("a".to_string());
    set.insert("b".to_string());

    // Not possible to collect to a Vec<String> with a regular `.iter()`.
    let v: Vec<String> = set.into_iter().collect();

    // Will print in an arbitrary order.
    for x in &v {
        println!("{}", x);
    }

Run
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