Rust:
将来または過去の日付を計算する

use chrono::{Duration, Utc};

fn main() {
    let today = Utc::now();
    println!("Today: {}", today);

    let future_date = today + Duration::days(30);
    println!("Future date: {}", future_date);

    let past_date = today - Duration::days(30);
    println!("Past date: {}", past_date);
}