rust - 如何使用分隔符将 HashSet 的元素连接到字符串中

Question

我可以做以下事情:

fn main() {
    let vec = vec!["first", "last"];
    println!("{}", vec.join(", "));
}

它给出了这个输出:

first, last

如果我尝试使用 join对于 map 类型，它失败了:

error[E0599]: no method named join found for type std::collections::HashSet<&str> in the current scope

Answer 1

更高效，您可以use itertools加入迭代器而不先将其收集到 Vec 中:

extern crate itertools;

use std::collections::HashSet;
use itertools::Itertools;

fn main() {
    let hash_set: HashSet<_> = ["first", "last"].iter().collect();

    // Either of
    println!("{}", hash_set.iter().join(", "));
    println!("{}", itertools::join(&hash_set, ", "));
}