How can I convert a string of numbers to an array or vector of integers in Rust?

Question

I\'m writing on STDIN a string of numbers (e.g 4 10 30 232312) and I want to read that and convert to an array (or a vector) of integers, but I can\'t find the

Answer 1

Safer version. This one skips failed parses so that failed unwrap doesn't panic. Use read_line for reading single line.

let mut buf = String::new();

// use read_line for reading single line 
std::io::stdin().read_to_string(&mut buf).expect("");

// this one skips failed parses so that failed unwrap doesn't panic
let v: Vec = buf
    .split_whitespace() // split string into words by whitespace
    .filter_map(|w| w.parse().ok()) // calling ok() turns Result to Option so that filter_map can discard None values
    .collect(); // collect items into Vector. This determined by type annotation.

You can even read Vector of Vectors like this.

let stdin = io::stdin();
let locked = stdin.lock();
let vv: Vec> = locked.lines()
    .filter_map(
        |l| l.ok().map(
            |s| s.split_whitespace()
                 .filter_map(|word| word.parse().ok())
                 .collect()))
    .collect();

Above one works for inputs like

2 424 -42 124
42 242 23 22 241
24 12 3 232 445

then turns them it into

[[2, 424, -42, 124],
[42, 242, 23, 22, 241],
[24, 12, 3, 232, 445]]

filter_map accepts a closure that returns Option and filters out all Nones.

ok() turns Result to Option so that errors can be filtered in this case.