# Date and Time Localization and Formatting
[](https://hex.pm/packages/ex_cldr_dates_times)
[](https://github.com/kipcole9/cldr_dates_times/blob/master/LICENSE)
## Introduction and Getting Started
`ex_cldr_dates_times` is an addon library application for [ex_cldr](https://hex.pm/packages/ex_cldr) that provides localisation and formatting for dates, times and date_times.
The primary api is `Cldr.Date.to_string/2`, `Cldr.Time.to_string/2` and `Cldr.DateTime.to_string/2`. The following examples demonstrate:
```elixir
iex> Cldr.Date.to_string Date.utc_today()
{:ok, "Aug 18, 2017"}
iex> Cldr.Time.to_string Time.utc_now
{:ok, "11:38:55 AM"}
iex> Cldr.DateTime.to_string DateTime.utc_now
{:ok, "Aug 18, 2017, 11:39:08 AM"}
iex> Cldr.DateTime.Relative.to_string 1, unit: :day, format: :narrow
{:ok, "tomorrow"}
```
For help in `iex`:
```elixir
iex> h Cldr.Date.to_string
iex> h Cldr.Time.to_string
iex> h Cldr.DateTime.to_string
iex> h Cldr.DateTime.Relative.to_string
```
## Documentation
Primary documentation is available on [as part of the ex_cldr documentation on hex](https://hexdocs.pm/ex_cldr/5_datetime_formats.html)
## Format strings
The [CLDR standard](http://unicode.org/reports/tr35/tr35-dates.html#Date_Field_Symbol_Table)
defines a wide range of format symbols. Most - but not all - of these symbols are supported in
`Cldr`. The supported symbols are described below. Note the [known restrictions and limitations](#known-restrictions-and-limitations).
| Element | Symbol | Example | Cldr Format |
| :-------------------- | :-------- | :-------------- | :--------------------------------- |
| Era | G, GG, GGG | "AD" | Abbreviated |
| | GGGG | "Anno Domini" | Wide |
| | GGGGG | "A" | Narrow |
| Year | y | 7 | Minimum necessary digits |
| | yy | "17" | Least significant 2 digits |
| | yyy | "017", "2017" | Padded to at least 3 digits |
| | yyyy | "2017" | Padded to at least 4 digits |
| | yyyyy | "02017" | Padded to at least 5 digits |
| ISOWeek Year | Y | 7 | Minimum necessary digits |
| | YY | "17" | Least significant 2 digits |
| | YYY | "017", "2017" | Padded to at least 3 digits |
| | YYYY | "2017" | Padded to at least 4 digits |
| | YYYYY | "02017" | Padded to at least 5 digits |
| Related Gregorian Year | r, rr, rr+ | 2017 | Minimum necessary digits |
| Cyclic Year | U, UU, UUU | "甲子" | Abbreviated |
| | UUUU | "甲子" (for now) | Wide |
| | UUUUU | "甲子" (for now) | Narrow |
| Extended Year | u+ | 4601 | Minimim necessary digits |
| Quarter | Q | 2 | Single digit |
| | QQ | "02" | Two digits |
| | QQQ | "Q2" | Abbreviated |
| | QQQQ | "2nd quarter" | Wide |
| | QQQQQ | "2" | Narrow |
| Standalone Quarter | q | 2 | Single digit |
| | qq | "02" | Two digits |
| | qqq | "Q2" | Abbreviated |
| | qqqq | "2nd quarter" | Wide |
| | qqqqq | "2" | Narrow |
| Month | M | 9 | Single digit |
| | MM | "09" | Two digits |
| | MMM | "Sep" | Abbreviated |
| | MMMM | "September" | Wide |
| | MMMMM | "S" | Narrow |
| Standalone Month | L | 9 | Single digit |
| | LL | "09" | Two digits |
| | LLL | "Sep" | Abbreviated |
| | LLLL | "September" | Wide |
| | LLLLL | "S" | Narrow |
| Week of Year | w | 2, 22 | Single digit |
| | ww | 02, 22 | Two digits, zero padded |
| Week of Month | W | 2 | Single digit |
| Day of Year | D | 3, 33, 333 | Minimum necessary digits |
| | DD | 03, 33, 333 | Minimum of 2 digits, zero padded |
| | DDD | 003, 033, 333 | Minimum of 3 digits, zero padded |
| Day of Month | d | 2, 22 | Minimum necessary digits |
| | dd | 02, 22 | Two digits, zero padded |
| Day of Week | E, EE, EEE | "Tue" | Abbreviated |
| | EEEE | "Tuesday" | Wide |
| | EEEEE | "T" | Narrow |
| | EEEEEE | "Tu" | Short |
| | e | 2 | Single digit |
| | ee | "02" | Two digits |
| | eee | "Tue" | Abbreviated |
| | eeee | "Tuesday" | Wide |
| | eeeee | "T" | Narrow |
| | eeeeee | "Tu" | Short |
| Standalone Day of Week | c, cc | 2 | Single digit |
| | ccc | "Tue" | Abbreviated |
| | cccc | "Tuesday" | Wide |
| | ccccc | "T" | Narrow |
| | cccccc | "Tu" | Short |
| AM or PM | a, aa, aaa | "am." | Abbreviated |
| | aaaa | "am." | Wide |
| | aaaaa | "am" | Narrow |
| Noon, Mid, AM, PM | b, bb, bbb | "mid." | Abbreviated |
| | bbbb | "midnight" | Wide |
| | bbbbb | "md" | Narrow |
| Flexible time period | B, BB, BBB | "at night" | Abbreviated |
| | BBBB | "at night" | Wide |
| | BBBBB | "at night" | Narrow |
| Hour | h, K, H, k | | See the table below |
| Minute | m | 3, 10 | Minimim digits of minutes |
| | mm | "03", "12" | Two digits, zero padded |
| Second | s | 3, 48 | Minimim digits of seconds |
| | ss | "03", "48" | Two digits, zero padded |
| Fractional Seconds | S | 3, 48 | Minimim digits of fractional seconds |
| | SS | "03", "48" | Two digits, zero padded |
| Millseconds | A+ | 4000, 63241 | Minimim digits of milliseconds since midnight |
| Generic non-location TZ | v | "Etc/UTC" | `:time_zone` key, unlocalised |
| | vvvv | "unk" | Generic timezone name. Currently returns only "unk" |
| Specific non-location TZ | z..zzz | "UTC" | `:zone_abbr` key, unlocalised |
| | zzzz | "GMT" | Delegates to `zone_gmt/4` |
| Timezone ID | V | "unk" | `:zone_abbr` key, unlocalised |
| | VV | "Etc/UTC | Delegates to `zone_gmt/4` |
| | VVV | "Unknown City" | Exemplar city. Not supported. |
| | VVVV | "GMT" | Delegates to `zone_gmt/4 |
| ISO8601 Format | Z..ZZZ | "+0100" | ISO8601 Basic Format with hours and minutes |
| | ZZZZ | "+01:00" | Delegates to `zone_gmt/4 |
| | ZZZZZ | "+01:00:10" | ISO8601 Extended format with optional seconds |
| ISO8601 plus Z | X | "+01" | ISO8601 Basic Format with hours and optional minutes or "Z" |
| | XX | "+0100" | ISO8601 Basic Format with hours and minutes or "Z" |
| | XXX | "+0100" | ISO8601 Basic Format with hours and minutes, optional seconds or "Z" |
| | XXXX | "+010059" | ISO8601 Basic Format with hours and minutes, optional seconds or "Z" |
| | XXXXX | "+01:00:10" | ISO8601 Extended Format with hours and minutes, optional seconds or "Z" |
| ISO8601 minus Z | x | "+0100" | ISO8601 Basic Format with hours and optional minutes |
| | xx | "-0800" | ISO8601 Basic Format with hours and minutes |
| | xxx | "+01:00" | ISO8601 Extended Format with hours and minutes |
| | xxxx | "+010059" | ISO8601 Basic Format with hours and minutes, optional seconds |
| | xxxxx | "+01:00:10" | ISO8601 Extended Format with hours and minutes, optional seconds |
| GMT Format | O | "+0100" | Short localised GMT format |
| | OOOO | "+010059" | Long localised GMT format |
## Formatting symbols for hour of day
The hour of day can be formatted differently depending whether
a 12- or 24-hour day is being represented and depending on the
way in which midnight and noon are represented. The following
table illustrates the differences:
| Symbol | Midn. | Morning | Noon | Afternoon | Midn. |
| :----: | :---: | :-----: | :--: | :--------: | :---: |
| h | 12 | 1...11 | 12 | 1...11 | 12 |
| K | 0 | 1...11 | 0 | 1...11 | 0 |
| H | 0 | 1...11 | 12 | 13...23 | 0 |
| k | 24 | 1...11 | 12 | 13...23 | 24 |
## Known restrictions and limitations
Although largely complete (with respect to the CLDR data), there are some known limitations as of release 0.1.0. These limitations will be removed before version 1.0.
* *Week of year* The week of year is returned for the format symbol `w`. Currently it considers weeks of the year to be those defined for the `ISOWeek` calendar. This means that January 1st may not be the start of the first week of the year and December 31st may not be the last day of the last week of the year.
* *Week of month* The week of the mornth is returned for format symbol `W`. Currently it considers weeks of the month to start on the first day of the month which is inconsistent with the ISOWeek standard and different from the `week_of_year` calculation.
* *Timezones* Although the timezone format codes are supported (formatting symbols `v`, `V`, `x`, `X`, `z`, `Z`, `O`) not all localisations are performed. Only that data available within a `DateTime` struct is used to format timezone data.
* *First day of week is always Monday* All formatting is done with Monday as the first day of the week. In several territories this is not a reasonable assumption. CLDR provides data to support a different starting day for the week. This will be implemented before version 1.0
* *Only calendar is Gregorian (Calendar.ISO)* CLDR defines many calendar systems (see `Cldr.Calendar.known_calendars/0`) however only Calendar.ISO (proleptic Gregorian calendar) is supported in this release.
* *Variants* Some formats defines variants in the CLDR data. For example, formatting an Era in the gregorian calendar is, by default, returned as `AD` or `BC`. CLDR also defines the variants `CE` and `BCE`. Currently the API does not provide a way to specify these variants.
## Installation
Note that `:ex_cldr_dates_times` requires Elixir 1.5 or later.
Add `ex_cldr_dates_time` as a dependency to your `mix` project:
defp deps do
[
{:ex_cldr_dates_times, "~> 0.2.1"}
]
end
then retrieve `ex_cldr_dates_times` from [hex](https://hex.pm/packages/ex_cldr_dates_times):
mix deps.get
mix deps.compile
