crates/csv/examples/tutorial-read-serde-01.rs

use std::{error::Error, io, process};

fn run() -> Result<(), Box<dyn Error>> {
    let mut rdr = csv::Reader::from_reader(io::stdin());
    for result in rdr.records() {
        let record = result?;

        let city = &record[0];
        let state = &record[1];
        // Some records are missing population counts, so if we can't
        // parse a number, treat the population count as missing instead
        // of returning an error.
        let pop: Option<u64> = record[2].parse().ok();
        // Lucky us! Latitudes and longitudes are available for every record.
        // Therefore, if one couldn't be parsed, return an error.
        let latitude: f64 = record[3].parse()?;
        let longitude: f64 = record[4].parse()?;

        println!(
            "city: {:?}, state: {:?}, \
             pop: {:?}, latitude: {:?}, longitude: {:?}",
            city, state, pop, latitude, longitude
        );
    }
    Ok(())
}

fn main() {
    if let Err(err) = run() {
        println!("{}", err);
        process::exit(1);
    }
}