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迭代器1： exercises/iterators/iterators1.rs
题目
rust
// iterators1.rs
//
// When performing operations on elements within a collection, iterators are
// essential. This module helps you get familiar with the structure of using an
// iterator and how to go through elements within an iterable collection.
//
// Make me compile by filling in the `???`s
//
// Execute `rustlings hint iterators1` or use the `hint` watch subcommand for a
// hint.
// I AM NOT DONE
fn main() {
let my_fav_fruits = vec!["banana", "custard apple", "avocado", "peach", "raspberry"];
let mut my_iterable_fav_fruits = ???; // TODO: Step 1
assert_eq!(my_iterable_fav_fruits.next(), Some(&"banana"));
assert_eq!(my_iterable_fav_fruits.next(), ???); // TODO: Step 2
assert_eq!(my_iterable_fav_fruits.next(), Some(&"avocado"));
assert_eq!(my_iterable_fav_fruits.next(), ???); // TODO: Step 3
assert_eq!(my_iterable_fav_fruits.next(), Some(&"raspberry"));
assert_eq!(my_iterable_fav_fruits.next(), ???); // TODO: Step 4
}当对集合中的元素执行操作时，迭代器是必不可少的。该模块可以帮助你熟悉使用迭代器的结构，以及如何遍历可迭代集合中的元素。
通过填写???的部分让编译和测试通过。
题目解析
迭代器模式允许你对一个序列的项进行某些处理。迭代器（iterator）负责遍历序列中的每一项和决定序列何时结束的逻辑。当使用迭代器时，我们无需重新实现这些逻辑。
rust
fn main() {
let my_fav_fruits = vec!["banana", "custard apple", "avocado", "peach", "raspberry"];
let mut my_iterable_fav_fruits = ???; // TODO: Step 1
let mut my_iterable_fav_fruits = my_fav_fruits.iter();
assert_eq!(my_iterable_fav_fruits.next(), Some(&"banana"));
assert_eq!(my_iterable_fav_fruits.next(), ???); // TODO: Step 2
assert_eq!(my_iterable_fav_fruits.next(), Some(&"custard apple"));
assert_eq!(my_iterable_fav_fruits.next(), Some(&"avocado"));
assert_eq!(my_iterable_fav_fruits.next(), ???); // TODO: Step 3
assert_eq!(my_iterable_fav_fruits.next(), Some(&"peach"));
assert_eq!(my_iterable_fav_fruits.next(), Some(&"raspberry"));
assert_eq!(my_iterable_fav_fruits.next(), ???); // TODO: Step 4
assert_eq!(my_iterable_fav_fruits.next(), None);
}