Parsing and Displaying

Examine the date and time

Gets the current UTC DateTime and its hour/minute/second via Timelike and its year/month/day/weekday via Datelike.

use chrono::{Datelike, Timelike, Utc};

fn main() {
    let now = Utc::now();

    let (is_pm, hour) = now.hour12();
    println!(
        "The current UTC time is {:02}:{:02}:{:02} {}",
        hour,
        now.minute(),
        now.second(),
        if is_pm { "PM" } else { "AM" }
    );
    println!(
        "And there have been {} seconds since midnight",
        now.num_seconds_from_midnight()
    );

    let (is_common_era, year) = now.year_ce();
    println!(
        "The current UTC date is {}-{:02}-{:02} {:?} ({})",
        year,
        now.month(),
        now.day(),
        now.weekday(),
        if is_common_era { "CE" } else { "BCE" }
    );
    println!(
        "And the Common Era began {} days ago",
        now.num_days_from_ce()
    );
}

Convert date to UNIX timestamp and vice versa

Converts a date given by NaiveDate::from_ymd and NaiveTime::from_hms to UNIX timestamp using NaiveDateTime::timestamp. Then it calculates what was the date after one billion seconds since January 1, 1970 0:00:00 UTC, using NaiveDateTime::from_timestamp.

use chrono::{NaiveDate, NaiveDateTime};

fn main() {
    if let Some(nov_2017_date) = NaiveDate::from_ymd_opt(2017, 11, 12) {
        if let Some(five_33) = nov_2017_date.and_hms_opt(17, 33, 44) {
            println!(
                "Number of seconds between 1970-01-01 00:00:00 and {} is {}.",
                five_33, five_33.timestamp());
        }
    }

    if let Some(date_time_after_a_billion_seconds) = NaiveDateTime::from_timestamp_opt(1_000_000_000, 0) {
        println!(
            "Date after a billion seconds since 1970-01-01 00:00:00 was {}.",
            date_time_after_a_billion_seconds);
    }
}

Display formatted date and time

Gets and displays the current time in UTC using Utc::now. Formats the current time in the well-known formats RFC 2822 using DateTime::to_rfc2822 and RFC 3339 using DateTime::to_rfc3339, and in a custom format using DateTime::format.

use chrono::{DateTime, Utc};

fn main() {
    let now: DateTime<Utc> = Utc::now();

    println!("UTC now is: {}", now);
    println!("UTC now in RFC 2822 is: {}", now.to_rfc2822());
    println!("UTC now in RFC 3339 is: {}", now.to_rfc3339());
    println!("UTC now in a custom format is: {}", now.format("%a %b %e %T %Y"));
}

Parse string into DateTime struct

Parses a DateTime struct from strings representing the well-known formats RFC 2822, RFC 3339, and a custom format, using DateTime::parse_from_rfc2822, DateTime::parse_from_rfc3339, and DateTime::parse_from_str respectively.

Escape sequences that are available for the DateTime::parse_from_str can be found at chrono::format::strftime. Note that the DateTime::parse_from_str requires that such a DateTime struct must be creatable that it uniquely identifies a date and a time. For parsing dates and times without timezones use NaiveDate, NaiveTime, and NaiveDateTime.

use chrono::{DateTime, NaiveDate, NaiveDateTime, NaiveTime};
use chrono::format::ParseError;


fn main() -> Result<(), ParseError> {
    let rfc2822 = DateTime::parse_from_rfc2822("Tue, 1 Jul 2003 10:52:37 +0200")?;
    println!("{}", rfc2822);

    let rfc3339 = DateTime::parse_from_rfc3339("1996-12-19T16:39:57-08:00")?;
    println!("{}", rfc3339);

    let custom = DateTime::parse_from_str("5.8.1994 8:00 am +0000", "%d.%m.%Y %H:%M %P %z")?;
    println!("{}", custom);

    let time_only = NaiveTime::parse_from_str("23:56:04", "%H:%M:%S")?;
    println!("{}", time_only);

    let date_only = NaiveDate::parse_from_str("2015-09-05", "%Y-%m-%d")?;
    println!("{}", date_only);

    let no_timezone = NaiveDateTime::parse_from_str("2015-09-05 23:56:04", "%Y-%m-%d %H:%M:%S")?;
    println!("{}", no_timezone);

    Ok(())
}