Rust：通过索引访问文件中的行，或者是否有另一种方法来比较两行

Question

i have a simple txt file with one value per line. Is it somehow possible to compare two lines?

I was looking for a way to index each line and then compare the index [n] with index [n+1]. By now i am able to print each line, but not to compare the entries.

Here is my code:

use std::fs::File;
use std::env;
use std::io::{self, BufReader, BufRead};


fn read_file(filename: &String) -> io::Result<()> {
    let file = File::open(filename)?;
    let content = BufReader::new(file);

    for line in content.lines() {
        println!("{}", line.unwrap());
    }

    Ok(())
}


fn main() {
    let args: Vec<String> = env::args().collect();
    let filename = &args[1];
    read_file(filename).expect("error reading file");
}

Answer 1

One solution is to collect all lines into a vector and use std::iter::zip function .

fn read_file(filename: &String) -> io::Result<()> {
    let file = File::open(filename)?;
    let content = BufReader::new(file);

    let lines: Vec<String> = content
        .lines()
        .map(|line| line.expect("Something went wrong"))
        .collect();
    
    for (current, next) in lines.iter().zip(lines.iter().skip(1)) {
        println!("{}, {}", current, next)
    }
    Ok(())
}

So for the input file having content,

1
2
3
4

read_file function will print

1, 2
2, 3
3, 4