How to Read a File Line by Line in Rust

Use std::fs::File with BufReader and the lines() iterator to read a file line by line.

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

fn main() -> io::Result<()> {
    let file = File::open("hello.txt")?;
    let reader = BufReader::new(file);

    for line in reader.lines() {
        let line = line?;
        println!("{line}");
    }
    Ok(())
}

Reading a file line by line in Rust opens the file and processes it one line at a time instead of loading the whole thing into memory at once. This approach is useful for handling large text files efficiently without crashing your computer. Think of it like reading a book page by page rather than trying to memorize the entire story before starting.