fn main() -> std::io::Result<()> { let mut reader = my_reader::BufReader::open("data.txt")?; let mut buffer = String::new(); while let Some(line) = reader.read_line(...
demo1:use std::fs::File; use std::io::{self, prelude::*, BufReader}; fn main() -> io::Result<()> { let file = File::open("data.txt")?; let reader = BufReader::new(file);...