itoa/README.md

itoa
====

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[![Latest Version](https://img.shields.io/crates/v/itoa.svg)](https://crates.io/crates/itoa)

This crate provides fast functions for printing integer primitives to an
[`io::Write`](https://doc.rust-lang.org/std/io/trait.Write.html) or a
[`fmt::Write`](https://doc.rust-lang.org/core/fmt/trait.Write.html). The
implementation comes straight from
[libcore](https://github.com/rust-lang/rust/blob/b8214dc6c6fc20d0a660fb5700dca9ebf51ebe89/src/libcore/fmt/num.rs#L201-L254)
but avoids the performance penalty of going through
[`fmt::Formatter`](https://doc.rust-lang.org/std/fmt/struct.Formatter.html).

See also [`dtoa`](https://github.com/dtolnay/dtoa) for printing floating point
primitives.

## Performance (lower is better)

![performance](https://raw.githubusercontent.com/dtolnay/itoa/master/performance.png)

## Functions

```rust
extern crate itoa;

// write to a vector or other io::Write
let mut buf = Vec::new();
itoa::write(&mut buf, 128u64)?;
println!("{:?}", buf);

// write to a stack buffer
let mut bytes = [b'\0'; 20];
let n = itoa::write(&mut bytes[..], 128u64)?;
println!("{:?}", &bytes[..n]);

// write to a String
let mut s = String::new();
itoa::fmt(&mut s, 128u64)?;
println!("{}", s);
```

The function signatures are:

```rust
fn write<W: io::Write, V: itoa::Integer>(writer: W, value: V) -> io::Result<usize>;

fn fmt<W: fmt::Write, V: itoa::Integer>(writer: W, value: V) -> fmt::Result;
```

where `itoa::Integer` is implemented for `i8`, `u8`, `i16`, `u16`, `i32`, `u32`,
`i64`, `u64`, `i128`, `u128`, `isize` and `usize`. 128-bit integer support is
only available with the nightly compiler when the `i128` feature is enabled for
this crate. The return value gives the number of bytes written.

The `write` function is only available when the `std` feature is enabled
(default is enabled).

## Dependency

Itoa is available on [crates.io](https://crates.io/crates/itoa). Use the
following in `Cargo.toml`:

```toml
[dependencies]
itoa = "0.3"
```

## License

Licensed under either of

 * Apache License, Version 2.0 ([LICENSE-APACHE](LICENSE-APACHE) or http://www.apache.org/licenses/LICENSE-2.0)
 * MIT license ([LICENSE-MIT](LICENSE-MIT) or http://opensource.org/licenses/MIT)

at your option.

### Contribution

Unless you explicitly state otherwise, any contribution intentionally submitted
for inclusion in itoa by you, as defined in the Apache-2.0 license, shall be
dual licensed as above, without any additional terms or conditions.