如何枚举字符串向量？

Question

let output_sorted: Vec<String> = four_digit_ouput
        .iter()
        .map(|tok| tok.chars().sorted().collect::<String>())
        .collect();

let output = 0;
for (idx, digit) in output_sorted.enumerate() {

当我尝试对字符串向量进行枚举 for 循环时出现此错误:

error[E0599]: the method `enumerate` exists for struct `Vec<String>`, but its trait bounds were not satisfied
   --> src\day8.rs:185:39
    |
185 |     for (idx, digit) in output_sorted.enumerate() {}
    |                                       ^^^^^^^^^ method cannot be called on `Vec<String>` due to unsatisfied trait bounds
    |
   ::: C:\Users\b\.rustup\toolchains\stable-x86_64-pc-windows-msvc\lib/rustlib/src/rust\library\alloc\src\vec\mod.rs:400:1
    |
400 | pub struct Vec<T, #[unstable(feature = "allocator_api", issue = "32838")] A: Allocator = Global> {
    | ------------------------------------------------------------------------------------------------ doesn't satisfy `Vec<String>: Iterator`
    |
    = note: the following trait bounds were not satisfied:
            `Vec<String>: Iterator`
            which is required by `&mut Vec<String>: Iterator`
            `[String]: Iterator`
            which is required by `&mut [String]: Iterator`
    
For more information about this error, try `rustc --explain E0599`.

这是怎么回事？什么特征界限不允许这个枚举？

Answer 1

矢量不是 Iterator。

使用output_sorted.iter().enumerate() (to consult), output_sorted.iter_mut().enumerate() (to modify) oroutput_sorted.into_iter().enumerate()（消费）。

请注意，当直接在向量上使用 for 循环时，会隐式调用 into_iter()；这可以解释为好像向量本身就是一个 Iterator 但这只是语言的一种方便。

如何枚举字符串向量？

How do I enumerate on a vector of Strings?

rust

iterator

enumerate