How to iterate and extract values out of a for loop in Rust

Question

I\'m new to Rust and looking to understand concepts like borrowing. I\'m trying to create a simple two dimensional array using standard input. The code:

use          


        

Answer 1

This answer was moved from the question, where it solved the OPs needs.

use std::io;

fn main() {
    let mut values = vec![vec![String::new(); 6]; 6];
    for i in 0..6 {
        let mut outputs = String::new();
        io::stdin().read_line(&mut outputs)
                .expect("failed to read line");

        let values_itr = outputs.trim().split(' ');
        let mut j = 0;
        for (_, value) in values_itr.enumerate() {
            values[i][j] = value.to_string();
            j += 1;
        }
    }
}

Answer 2

split() gives you substrings (string slices) borrowed from the original string, and the original string is outputs from line 6.

1. The string slices can't outlive the scope of outputs: when a loop iteration ends, outputs is deallocated. Since values is longer lived, the slices can't be stored there.
2. We can't borrow slices of outputs across a modification of outputs. So even if the String outputs itself was defined before values, we couldn't easily put the string slices from .split() into values; modifying the string (reading into it) invalidates the slices.

A solution needs to either

• Use a nested array of String, and when you assign an element from the split iterator, make a String from the &str using .to_string(). I would recommend this solution. (However an array of String is not at as easy to work with, maybe already this requires using Vec instead.) ¹
• Read all input before constructing a nested array of &str that borrows from the input String. This is good if the nested array is something that you only need temporarily.

¹: You can use something like vec![vec![String::new(); 6]; 6] instead