1 use std::error::Error; 2 use std::io::{self, BufRead, Write}; 3 main() -> Result<(), Box<dyn Error>>4fn main() -> Result<(), Box<dyn Error>> { 5 let stdin = io::stdin(); 6 let mut stdin = stdin.lock(); 7 let mut stdout = io::BufWriter::new(io::stdout()); 8 9 let mut line = String::new(); 10 while stdin.read_line(&mut line)? > 0 { 11 stdout.write_all(line.to_uppercase().as_bytes())?; 12 line.clear(); 13 } 14 Ok(()) 15 } 16