制作 hashMap 时遇到问题，无法理解错误，完整示例答案

【问题标题】：Having problems making a hashMap, can't understand error, full example制作 hashMap 时遇到问题，无法理解错误，完整示例
【发布时间】：2021-12-13 06:19:07
【问题描述】：

认为这很简单。

只想创建一个哈希映射，其中键是一个元组 (u8, &str)，表示一组有序问题的数量，而字符串文字表示问题本身。然后值将是另一个元组 (&str, [&str;4]) 代表正确的字母和可能的答案

const ANSWER_KEY: HashMap<(u8, &str), (&str, [&str;4])> = HashMap::from {
    (1, "What is a programming language?") : ("B", [
        "A. A language that improves programming.",
        "B. A human readable language for humans that translates to a binary language to communicate with computers.",
        "C. A language read by computers that translates to a unary language to communicate with humans.",
        "D. A language created by Alan Turing.")
    ]
};

错误信息是："What is a programmi...' unexpected和<struct literal field> expected, got '('

【问题讨论】：

HashMap::from { key: value, ... } 语法无效。也许你想要HashMap::from([(key, value), ...]) 就像这个答案：stackoverflow.com/a/69640610/2189130
谢谢你是def。一个错误但虽然现在错误是mismatched types [E0308] expected [((u8, &str), (&str, [&str; 4])); ], found (i32, &str)` `
另外，如果问答是有序和编号的，为什么还要使用哈希图？ Vec 不是更合适吗？
@kmdreko 是的，元组的 vec 听起来更合适

标签： rust

【解决方案1】：

你可以这样声明：

let answer: HashMap<(u8, &str), (&str, [&str;4])> = HashMap::from(
[
    ((1, "What is a programming language?"), ("B", [
    "A. A language that improves programming.",
    "B. A human readable language for humans that translates to a binary language to communicate with computers.",
    "C. A language read by computers that translates to a unary language to communicate with humans.",
    "D. A language created by Alan Turing."]))
]);

由于错误 [E0015]，您无法声明 const：常量中的调用仅限于常量函数、元组结构和元组变体

【讨论】：