# rusty-money   [![Build Status]][travis] [![Latest Version]][crates.io] [![Docs]][docs.rs]
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rusty-money handles the messy parts of dealing with money like rounding, precision, parsing and internationalization.
It supports [ISO-4217](https://en.wikipedia.org/wiki/ISO_4217) currencies, common crypto currencies and lets you
define your own. The main items exported by the library are `Money` and the `iso` and `crypto` currency sets.
## Usage
A `Money` object is created by supplying an amount and a currency. Amounts can be specified in numeric or string types
but will be stored as precise decimals internally. You can select a bundled currency or make your own. Here's a
quick example of how you would make your own `Currency` and then create some `Money` with it:
```rust
use rusty-money::{Money, define_currency_set};
define_currency_set!(
video_game {
GIL: {
code: "GIL",
exponent: 2,
locale: Locale::EnUs,
minor_units: 100,
name: "GIL",
symbol: "G",
symbol_first: true,
}
}
);
Money::from_major(2_000, video_game::GIL); // 2000 GIL
Money::from_minor(200_000, video_game::GIL); // 2000 GIL
Money::from_str("2,000.00", video_game::GIL).unwrap(); // 2000 GIL
// Currencies can be looked up by code.
let gil = video_game::find("GIL").unwrap();
Money::from_major(2_000, gil); // 2000 GIL
```
## Features: Currency Sets
rusty_money provides two currency sets for convenience : `iso`, which implements ISO-4217 currencies and `crypto` which
implements popular cryptocurencies. `iso` is enabled by default, and you can add `crypto` by enabling the feature:
```toml
[dependencies]
rusty-money = { version = "0.4.0", features = ["iso", "crypto"] }
```
The currency sets can then be used like this:
```rust
use rusty-money::{Money, iso, crypto};
Money::from_major(2_000, iso::USD); // 2000 U.S Dollars
Money::from_major(2_000, iso::GBP); // 2000 British Pounds
Money::from_major(2, crypto::BTC); // 2 Bitcoin
```
Money objects of the same currency can be compared:
```rust
use rusty-money::{Money, iso};
let hundred = Money::from_minor(10_000, iso::USD);
let thousand = Money::from_minor(100_000, iso::USD);
println!("{}", thousand > hundred); // false
println!("{}", thousand.is_positive()); // true
```
## Precision, Rounding and Math
Money objects are immutable, and operations that change amounts create a new instance of Money. Amounts are stored
as 128 bit fixed-precision [Decimals](https://github.com/paupino/rust-decimal), and handle values as large as
2<sup>96</sup> / 10<sup>28</sup>. Operations on Money retain the maximum possible precision. When you want less
precision, you call the `round` function, which supports three modes:
* [Half Up](https://en.wikipedia.org/wiki/Rounding#Round_half_up)
* [Half Down](https://en.wikipedia.org/wiki/Rounding#Round_half_down)
* [Half Even](https://en.wikipedia.org/wiki/Rounding#Round_half_even) (default)
Money can be added, subtracted, multiplied and divided like this:
```rust
use rusty-money::{Money, Round, iso};
Money::from_minor(100, iso::USD) + Money::from_minor(100, iso::USD); // 2 USD
Money::from_minor(100, iso::USD) - Money::from_minor(100, iso::USD); // 0 USD
Money::from_minor(100, iso::USD) * 3; // 3 USD
Money::from_minor(100, iso::USD) / 3; // 0.333... USD
let usd = Money::from_str("-2000.005", iso::USD).unwrap(); // 2000.005 USD
usd.round(2, Round::HalfEven); // 2000.00 USD
usd.round(2, Round::HalfUp); // 2000.01 USD
usd.round(0, Round::HalfUp); // 2000 USD
```
## Formatting
Calling `format!` or `println!` on Money returns a string with a rounded amount, using separators and symbols
according to the locale of the currency. If you need to customize this output, the `Formatter` module
accepts a more detailed set of parameters.
```rust
use rusty-money::{Money, iso};
let usd = Money::from_str("-2000.009", iso::USD).unwrap();
let eur = Money::from_str("-2000.009", iso::EUR).unwrap();
println!("{}", usd); // -$2,000.01
println!("{}", eur); // -€2.000,01;
```
## Exchange
The library also provides two additional types - `Exchange` and `ExchangeRates` to convert Money from one currency
to another.
```rust
use rusty-money::{Money, Exchange, ExchangeRate, iso};
use rust_decimal_macros::*;
// Convert 1000 USD to EUR at a 2:1 exchange rate.
let rate = ExchangeRate::new(iso::USD, iso::EUR, dec!(0.5)).unwrap();
rate.convert(Money::from_minor(100_000, iso::USD)); // 500 EUR
// An Exchange can be used to store ExchangeRates for later use
let mut exchange = Exchange::new();
exchange.set_rate(&rate);
exchange.get_rate(iso::USD, iso::EUR);
```