std::collections::hash_map::VacantEntry - Rust
Description: API documentation for the Rust `VacantEntry` struct in crate `std`.
Keywords: rust, rustlang, rust-lang, VacantEntry

# Struct std::collections::hash_map::VacantEntry 1.0.0 [−] [src]

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

A view into a vacant entry in a `HashMap`. It is part of the `Entry` enum.

## Methods

### `impl<'a, K: 'a, V: 'a> VacantEntry<'a, K, V>`
[src]

####
ⓘ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`
`pub fn key(&self) -> &K`
1.10.0
[src]

Gets a reference to the key that would be used when inserting a value through the `VacantEntry`.

# Examples

    use std::collections::HashMap;

    let mut map: HashMap<&str, u32> = HashMap::new();
    assert_eq!(map.entry("poneyland").key(), &"poneyland");Run

#### `pub fn into_key(self) -> K`
1.12.0
[src]

Take ownership of the key.

# Examples

    use std::collections::HashMap;
    use std::collections::hash_map::Entry;

    let mut map: HashMap<&str, u32> = HashMap::new();

    if let Entry::Vacant(v) = map.entry("poneyland") {
        v.into_key();
    }Run

####
ⓘ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`
`pub fn insert(self, value: V) -> &'a mut V`
[src]

Sets the value of the entry with the VacantEntry's key, and returns a mutable reference to it.

# Examples

    use std::collections::HashMap;
    use std::collections::hash_map::Entry;

    let mut map: HashMap<&str, u32> = HashMap::new();

    if let Entry::Vacant(o) = map.entry("poneyland") {
        o.insert(37);
    }
    assert_eq!(map["poneyland"], 37);Run

## Trait Implementations

### `impl<'a, K: 'a + Debug, V: 'a> Debug for VacantEntry<'a, K, V>`
1.12.0
[src]

#### `fn fmt(&self, f: &mut Formatter) -> Result`
[src]

Formats the value using the given formatter. Read more

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