Read an ascii char from stdin in Rust.

read_char.rs

use std::io::{Read, stdin};

/*
    return: Some(char) on success, None on EOF or error.
*/
fn read_char() -> Option<char> {
    stdin().bytes().next().and_then(|res| res.ok()).map(|c| {
        char::from(c)
    })
}
  
// res is of type: Result<u8, std::io::Error>
// use res.ok() to turn it into Option<u8>
// and then map Option<u8> to Option<char>