How to check for EOF with `read_line()`?

Question

Given the code below, how can I specifically check for EOF? Or rather, how can I distinguish between \"there\'s nothing here\" and \"it exploded\"?

match io:         


        

Answer 1

From the documentation for read_line:

If successful, this function will return the total number of bytes read.

If this function returns Ok(0), the stream has reached EOF.

This means we can check for a successful value of zero:

use std::io::{self, BufRead};

fn main() -> io::Result<()> {
    let mut empty: &[u8] = &[];
    let mut buffer = String::new();

    let bytes = empty.read_line(&mut buffer)?;
    if bytes == 0 {
        println!("EOF reached");
    }

    Ok(())
}