# icu_plurals [](https://crates.io/crates/icu_plurals)
Determine the plural category appropriate for a given number in a given language.
This module is published as its own crate ([`icu_plurals`](https://docs.rs/icu_plurals/latest/icu_plurals/))
and as part of the [`icu`](https://docs.rs/icu/latest/icu/) crate. See the latter for more details on the ICU4X project.
For example in English, when constructing a message
such as `{ num } items`, the user has to prepare
two variants of the message:
* `1 item`
* `0 items`, `2 items`, `5 items`, `0.5 items` etc.
The former variant is used when the placeholder variable has value `1`,
while the latter is used for all other values of the variable.
Unicode defines [Language Plural Rules] as a mechanism to codify those
variants and provides data and algorithms to calculate
appropriate [`PluralCategory`].
## Examples
```rust
use icu::locid::locale;
use icu::plurals::{PluralCategory, PluralRuleType, PluralRules};
let pr =
PluralRules::try_new(&locale!("en").into(), PluralRuleType::Cardinal)
.expect("locale should be present");
assert_eq!(pr.category_for(5_usize), PluralCategory::Other);
```
### Plural Rules
The crate provides the main struct [`PluralRules`] which handles selection
of the correct [`PluralCategory`] for a given language and [`PluralRuleType`].
### Plural Category
Every number in every language belongs to a certain [`PluralCategory`].
For example, the Polish language uses four:
* [`One`](PluralCategory::One): `1 miesiąc`
* [`Few`](PluralCategory::Few): `2 miesiące`
* [`Many`](PluralCategory::Many): `5 miesięcy`
* [`Other`](PluralCategory::Other): `1.5 miesiąca`
### `PluralRuleType`
Plural rules depend on the use case. This crate supports two types of plural rules:
* [`Cardinal`](PluralRuleType::Cardinal): `3 doors`, `1 month`, `10 dollars`
* [`Ordinal`](PluralRuleType::Ordinal): `1st place`, `10th day`, `11th floor`
[Language Plural Rules]: https://unicode.org/reports/tr35/tr35-numbers.html#Language_Plural_Rules
## More Information
For more information on development, authorship, contributing etc. please visit [`ICU4X home page`](https://github.com/unicode-org/icu4x).