【Rust】迭代器(三)
阿新 • • 發佈:2022-05-28
環境
- Time 2022-03-22
- Rust 1.59.0
示例
take_while
在找到返回 false 的值後,忽略剩餘所有元素。
fn main() {
let vec = vec![0, 1, 2, 3, 4];
vec.iter()
.take_while(|&e| e % 2 == 0)
.for_each(|e| println!("{e:?}"));
}
take
獲取幾個元素。
fn main() { let vec = vec![0, 1, 2, 3, 4]; vec.iter().take(2).for_each(|e| println!("{e:?}")); }
map_while
在找到返回 false 的值後,忽略剩餘所有元素。
fn main() {
let vec = vec!["0", "1", "two", "NaN", "four", "4"];
vec.iter()
.map_while(|e| e.parse().ok())
.for_each(|e: i32| println!("{e:?}"));
}
scan
fn main() { let vec = vec![0, 1, 2, 3, 4]; vec.iter() .scan(44, |e, &i| { *e += i; Some(*e) }) .for_each(|e| println!("{e:?}")); }
flat_map
fn main() {
let vec = ["jiang", "bo", "44"];
vec.iter()
.flat_map(|s| s.chars())
.for_each(|c| println!("{c}"));
}
flatten
fn main() {
let vec = vec![vec!["jiang", "bo"], vec!["44"]];
vec.iter().flatten().for_each(|e| println!("{e}"));
}
inspect
fn main() { let vec = vec![0, 1, 2, 3, 4]; vec.iter() .inspect(|e| println!("before: {e:?}")) .filter(|&e| e % 2 == 0) .for_each(|e| println!("{e}")); }
by_ref
fn main() {
let mut words = vec!["hello", "world", "Rust"].into_iter();
words.by_ref().take(2).for_each(|e| println!("{e}"));
words.for_each(|e| println!("{e}"));
}
總結
瞭解了迭代器中相關的一些方法。