# About
Date/time library
*See also the [API documentation] and [dtg] crate.*
[API documentation]: https://docs.rs/dtg-lib
[dtg]: https://crates.io/crates/dtg
# Examples
```Rust
use chrono::{TimeZone, Utc};
use dtg_lib::{tz, Dtg, Format};
let epoch = 1658448142;
let nanoseconds = 936196858;
let rfc_3339 = "2022-07-22T00:02:22Z";
let default_utc = "Fri 22 Jul 2022 00:02:22 UTC";
let default_mt = "Thu 21 Jul 2022 18:02:22 MDT";
let x = "Xg6L02M";
let a_utc = format!("{epoch}.000000000\n{rfc_3339}\n{default_utc}\n{default_utc}");
let a_mt = format!("{epoch}.000000000\n{rfc_3339}\n{default_utc}\n{default_mt}");
let day_of_week_utc = "Friday";
let day_of_week_mt = "Thursday";
let tz_utc = tz("UTC").ok();
let tz_mt = tz("MST7MDT").ok();
let default_fmt = Some(Format::default());
let day_of_week_fmt = Some(Format::custom("%A"));
// Create Dtg
let dtg_1_str = format!("{}", epoch);
let dtg_1_ts = Dtg::from(&dtg_1_str).unwrap();
let dtg_1_dt = Dtg::from_dt(&Utc.timestamp(epoch, 0));
let dtg_1_x = Dtg::from_x(x).unwrap();
assert_eq!(dtg_1_ts, dtg_1_dt);
assert_eq!(dtg_1_dt, dtg_1_x);
assert_eq!(dtg_1_x, dtg_1_ts);
// Create Dtg with nanoseconds
let dtg_2_str = format!("{}.{}", epoch, nanoseconds);
let dtg_2_ts = Dtg::from(&dtg_2_str).unwrap();
let dtg_2_dt = Dtg::from_dt(&Utc.timestamp(epoch, nanoseconds));
assert_eq!(dtg_2_ts, dtg_2_dt);
// Default format
assert_eq!(dtg_1_ts.default(&None), default_utc);
assert_eq!(dtg_1_ts.default(&tz_utc), default_utc);
assert_eq!(dtg_1_ts.default(&tz_mt), default_mt);
assert_eq!(dtg_1_ts.format(&default_fmt, &None), default_utc);
assert_eq!(dtg_1_ts.format(&default_fmt, &tz_utc), default_utc);
assert_eq!(dtg_1_ts.format(&default_fmt, &tz_mt), default_mt);
// RFC 3339 format
assert_eq!(dtg_1_ts.rfc_3339(), rfc_3339);
assert_eq!(dtg_1_ts.format(&None, &None), rfc_3339);
// "x" format
assert_eq!(dtg_1_ts.x_format(), x);
assert_eq!(dtg_1_ts.format(&Some(Format::X), &None), x);
// "a" format
assert_eq!(dtg_1_ts.a_format(&None), a_utc);
assert_eq!(dtg_1_ts.a_format(&tz_utc), a_utc);
assert_eq!(dtg_1_ts.a_format(&tz_mt), a_mt);
assert_eq!(dtg_1_ts.format(&Some(Format::A), &None), a_utc);
assert_eq!(dtg_1_ts.format(&Some(Format::A), &tz_utc), a_utc);
assert_eq!(dtg_1_ts.format(&Some(Format::A), &tz_mt), a_mt);
// Custom format
assert_eq!(dtg_1_ts.format(&day_of_week_fmt, &None), day_of_week_utc);
assert_eq!(dtg_1_ts.format(&day_of_week_fmt, &tz_mt), day_of_week_mt);
```
# Formats
## Date specifiers
`%Y` | `2001` | The full proleptic Gregorian year, zero-padded to 4 digits.
`%C` | `20` | The proleptic Gregorian year divided by 100, zero-padded to 2 digits.
`%y` | `01` | The proleptic Gregorian year modulo 100, zero-padded to 2 digits.
`%m` | `07` | Month number (01--12), zero-padded to 2 digits.
`%b` | `Jul` | Abbreviated month name. Always 3 letters.
`%B` | `July` | Full month name. Also accepts corresponding abbreviation in parsing.
`%h` | `Jul` | Same as `%b`.
`%d` | `08` | Day number (01--31), zero-padded to 2 digits.
`%e` | ` 8` | Same as `%d` but space-padded. Same as `%_d`.
`%a` | `Sun` | Abbreviated weekday name. Always 3 letters.
`%A` | `Sunday` | Full weekday name. Also accepts corresponding abbreviation in parsing.
`%w` | `0` | Sunday = 0, Monday = 1, ..., Saturday = 6.
`%u` | `7` | Monday = 1, Tuesday = 2, ..., Sunday = 7. (ISO 8601)
`%U` | `28` | Week number starting with Sunday (00--53), zero-padded to 2 digits.
`%W` | `27` | Same as `%U`, but week 1 starts with the first Monday in that year instead.
`%G` | `2001` | Same as `%Y` but uses the year number in ISO 8601 week date.
`%g` | `01` | Same as `%y` but uses the year number in ISO 8601 week date.
`%V` | `27` | Same as `%U` but uses the week number in ISO 8601 week date (01--53).
`%j` | `189` | Day of the year (001--366), zero-padded to 3 digits.
`%D` | `07/08/01` | Month-day-year format. Same as `%m/%d/%y`.
`%x` | `07/08/01` | Locale's date representation (e.g., 12/31/99).
`%F` | `2001-07-08` | Year-month-day format (ISO 8601). Same as `%Y-%m-%d`.
`%v` | ` 8-Jul-2001` | Day-month-year format. Same as `%e-%b-%Y`.
## Time specifiers
`%H` | `00` | Hour number (00--23), zero-padded to 2 digits.
`%k` | ` 0` | Same as `%H` but space-padded. Same as `%_H`.
`%I` | `12` | Hour number in 12-hour clocks (01--12), zero-padded to 2 digits.
`%l` | `12` | Same as `%I` but space-padded. Same as `%_I`.
`%P` | `am` | `am` or `pm` in 12-hour clocks.
`%p` | `AM` | `AM` or `PM` in 12-hour clocks.
`%M` | `34` | Minute number (00--59), zero-padded to 2 digits.
`%S` | `60` | Second number (00--60), zero-padded to 2 digits.
`%f` | `026490000` | The fractional seconds (in nanoseconds) since last whole second.
`%.f` | `.026490` | Similar to `.%f` but left-aligned. These all consume the leading dot.
`%.3f` | `.026` | Similar to `.%f` but left-aligned but fixed to a length of 3.
`%.6f` | `.026490` | Similar to `.%f` but left-aligned but fixed to a length of 6.
`%.9f` | `.026490000` | Similar to `.%f` but left-aligned but fixed to a length of 9.
`%3f` | `026` | Similar to `%.3f` but without the leading dot.
`%6f` | `026490` | Similar to `%.6f` but without the leading dot.
`%9f` | `026490000` | Similar to `%.9f` but without the leading dot.
`%R` | `00:34` | Hour-minute format. Same as `%H:%M`.
`%T` | `00:34:60` | Hour-minute-second format. Same as `%H:%M:%S`.
`%X` | `00:34:60` | Locale's time representation (e.g., 23:13:48).
`%r` | `12:34:60 AM` | Hour-minute-second format in 12-hour clocks. Same as `%I:%M:%S %p`.
## Time zone specifiers
`%Z` | `ACST` | Local time zone name. Skips all non-whitespace characters during parsing.
`%z` | `+0930` | Offset from the local time to UTC (with UTC being `+0000`).
`%:z` | `+09:30` | Same as `%z` but with a colon.
`%#z` | `+09` | *Parsing only:* Same as `%z` but allows minutes to be missing or present.
## Date & time specifiers
`%c` | `Sun Jul 8 00:34:60 2001` | Locale's date and time (e.g., Thu Mar 3 23:05:25 2005).
`%+` | `2001-07-08T00:34:60.026490+09:30` | ISO 8601 / RFC 3339 date & time format.
`%s` | `994518299` | UNIX timestamp, the number of seconds since 1970-01-01 00:00 UTC.
## Special specifiers
`%t` | Literal tab (`\t`).
`%n` | Literal newline (`\n`).
`%%` | Literal percent sign.