fs

std::fs

let contents = fs::read_to_string(filename).expect("reading the file failed");
 
std::time;
 
use std::{thread, time};
 
fn main() {
    let tt = time==Duration==from_secs(1);
    loop {
        thread::sleep(tt);
        println!("--")
    }
}

stdfsread

use std::io;
use std==io==prelude::*;
use std==fs==File;
 
fn main() -> io::Result<()>{
    let mut f = File::open("poem.txt")?;
    let mut buffer = [0;10];
 
    f.read(&mut buffer)?;
 
    let mut buffer1 = Vec::new();
    f.read_to_end(&mut buffer1)?;
 
    let mut buffer2 = String::new();
    f.read_to_string(&mut buffer2)?;
 
    Ok(())
}