1 use std::{env, error::Error, ffi::OsString, process};
2
run() -> Result<(), Box<dyn Error>>3 fn run() -> Result<(), Box<dyn Error>> {
4 let file_path = get_first_arg()?;
5 let mut wtr = csv::Writer::from_path(file_path)?;
6
7 wtr.write_record(&[
8 "City",
9 "State",
10 "Population",
11 "Latitude",
12 "Longitude",
13 ])?;
14 wtr.write_record(&[
15 "Davidsons Landing",
16 "AK",
17 "",
18 "65.2419444",
19 "-165.2716667",
20 ])?;
21 wtr.write_record(&["Kenai", "AK", "7610", "60.5544444", "-151.2583333"])?;
22 wtr.write_record(&["Oakman", "AL", "", "33.7133333", "-87.3886111"])?;
23
24 wtr.flush()?;
25 Ok(())
26 }
27
28 /// Returns the first positional argument sent to this process. If there are no
29 /// positional arguments, then this returns an error.
get_first_arg() -> Result<OsString, Box<dyn Error>>30 fn get_first_arg() -> Result<OsString, Box<dyn Error>> {
31 match env::args_os().nth(1) {
32 None => Err(From::from("expected 1 argument, but got none")),
33 Some(file_path) => Ok(file_path),
34 }
35 }
36
main()37 fn main() {
38 if let Err(err) = run() {
39 println!("{}", err);
40 process::exit(1);
41 }
42 }
43