rust - 如何从文件中读取字符串，将其拆分，然后在一条语句中创建Vec <＆str>？

Question

我需要有关如何将作为字符串的文件输入转换为向量的帮助。
我试过了

let content = fs::read_to_string(file_path).expect("Failed to read input");
let content: Vec<&str> = content.split("\n").collect();

这行得通，但我想将其转换为一条语句。就像是

let content: Vec<&str> = fs::read_to_string(file_path)
    .expect("Failed to read input")
    .split("\n")
    .collect();

我尝试使用

let content: Vec<&str> = match fs::read_to_string(file_path) {
    Ok(value) => value.split("\n").collect(),
    Err(err) => {
        println!("Error Unable to read the file {}", err);
        return ();
    }
};

和

let content: Vec<&str> = match fs::read_to_string(file_path) {
    Ok(value) => value,
    Err(err) => {
        println!("Error Unable to read the file {}", err);
        return ();
    }
}
.split("\n")
.collect();

编译器说，借入的值没有足够长的生命周期(第一个)，而在使用中却释放了值(第二个)(借入，范围和所有权存在问题)。

error[E0716]: temporary value dropped while borrowed
 --> src/lib.rs:4:26
  |
4 |   let content: Vec<&str> = fs::read_to_string("")
  |  __________________________^
5 | |     .expect("Failed to read input")
  | |___________________________________^ creates a temporary which is freed while still in use
6 |       .split("\n")
7 |       .collect();
  |                 - temporary value is freed at the end of this statement
8 |       
9 |       dbg!(content);
  |            ------- borrow later used here
  |
  = note: consider using a `let` binding to create a longer lived value

对于如何修复它们，我仍然缺乏足够的了解。

Answer 1

用一个表达式不可能做到这一点。就像您已经使用的那样，并按照编译器告诉您的那样，使用两个带有let的表达式。

问题在于split会生成引用临时&str的字符串切片(String)。该String在语句的末尾被释放，从而使引用无效。 Rust阻止您引入内存不安全性:

fs::read_to_string(file_path)        // Creates a String
    .expect("Failed to read input")
    .split("\n")                     // Takes references into the String
    .collect();                      // String is dropped, invalidating references

如果您不需要 Vec<&str>，则可以使用 Vec<String>:

fs::read_to_string(file_path)
    .expect("Failed to read input")
    .split("\n")
    .map(|s| s.to_string())         // Convert &str to String
    .collect();

也可以看看:

Temporary value dropped while borrowed, but I don't want to do a let

Using a `let` binding to increase a values lifetime

"borrowed value does not live long enough" seems to blame the wrong thing

Why does the compiler tell me to consider using a `let` binding" when I already am?

Do I need to use a `let` binding to create a longer lived value?

Why is it legal to borrow a temporary?