Trait Len

pub trait Len: Empty {
    // Required method
    fn len(&self) -> usize;
}

A trait for describing the length of a collection.

The amount of data stored in a collection, i.e. the amount of space it requires in memory, is directly proportional to its length. For this reason, str and other types measure their lengths in code values (e.g. u8), not code points (e.g. char).

Obtaining the length of the collection must take a constant amount of time and space.

Required Methods

fn len(&self) -> usize

Returns the length of the collection.

Examples

use len_trait::Len;

fn print_len<C: ?Sized + Len>(collection: &C) {
    println!("{} units long", collection.len());
}

print_len("中文");         // 6 units long
print_len(&[1, 2, 3][..]); // 3 units long

Implementations on Foreign Types

impl Len for str

fn len(&self) -> usize

impl Len for CString

fn len(&self) -> usize

impl Len for String

fn len(&self) -> usize

impl Len for CStr

fn len(&self) -> usize

impl Len for OsStr

fn len(&self) -> usize

impl Len for OsString

fn len(&self) -> usize

impl<K: Eq + Hash, V> Len for HashMap<K, V>

fn len(&self) -> usize

impl<K: Ord, V> Len for BTreeMap<K, V>

fn len(&self) -> usize

impl<T> Len for [T]

fn len(&self) -> usize

impl<T> Len for LinkedList<T>

fn len(&self) -> usize

impl<T> Len for VecDeque<T>

fn len(&self) -> usize

impl<T> Len for Vec<T>

fn len(&self) -> usize

impl<T: Eq + Hash> Len for HashSet<T>

fn len(&self) -> usize

impl<T: Ord> Len for BinaryHeap<T>

fn len(&self) -> usize

impl<T: Ord> Len for BTreeSet<T>

fn len(&self) -> usize

impl<T: ?Sized + Len> Len for Box<T>

fn len(&self) -> usize

impl<T: ?Sized + Len> Len for Rc<T>

fn len(&self) -> usize

impl<T: ?Sized + Len> Len for Arc<T>

fn len(&self) -> usize

Implementors