Peek迭代器在“loop”循环中

Question

在迭代&str时，我试图查看当前位置前面的字符。

let myStr = "12345";
let mut iter = myStr.chars().peekable();
for c in iter {
    let current: char = c;
    let next: char = *iter.peek().unwrap_or(&'∅');
}

我将把这个字符向下传递到一个方法中。然而，即使这个MRE产生了一个在移动错误后的借用，我不知道如何通过。

error[E0382]: borrow of moved value: `iter`
   --> src/lib.rs:7:27
    |
4   |     let mut iter = myStr.chars().peekable();
    |         -------- move occurs because `iter` has type `Peekable<Chars<'_>>`, which does not implement the `Copy` trait
5   |     for c in iter {
    |              ---- `iter` moved due to this implicit call to `.into_iter()`
6   |         let current: char = c;
7   |         let next: char = *iter.peek().unwrap_or(&'∅');
    |                           ^^^^^^^^^^^ value borrowed here after move
    |
note: this function takes ownership of the receiver `self`, which moves `iter`
   --> /home/james/.rustup/toolchains/stable-x86_64-unknown-linux-gnu/lib/rustlib/src/rust/library/core/src/iter/traits/collect.rs:267:18
    |
267 |     fn into_iter(self) -> Self::IntoIter;

知道这是怎么回事吗？我尝试过引用和取消引用的各种组合，但我尝试过的任何东西似乎都没有效果。

Answer 1

迭代器被移动到for循环中。您不能在for循环中手动操作迭代器。但是，for循环可以被while let替换。

while let Some(c) = iter.next() {
    let current: char = c;
    let next: char = *iter.peek().unwrap_or(&'∅');
}

游乐场。

Answer 2

如果您可以使用片，那么使用windows()将变得更加容易。

let slice = ['1', '2', '3', '4', '5'];
let iter = slice.windows(2);
for arr in iter {
    let current = arr[0];
    let next = arr[1];
}

游乐场