93 lines
2.7 KiB
Markdown
93 lines
2.7 KiB
Markdown
itoa
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====
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[](https://travis-ci.org/dtolnay/itoa)
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[](https://crates.io/crates/itoa)
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[](https://docs.rs/itoa)
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This crate provides fast functions for printing integer primitives to an
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[`io::Write`] or a [`fmt::Write`]. The implementation comes straight from
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[libcore] but avoids the performance penalty of going through
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[`fmt::Formatter`].
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See also [`dtoa`] for printing floating point primitives.
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*Version requirement: rustc 1.0+*
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[`io::Write`]: https://doc.rust-lang.org/std/io/trait.Write.html
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[`fmt::Write`]: https://doc.rust-lang.org/core/fmt/trait.Write.html
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[libcore]: https://github.com/rust-lang/rust/blob/b8214dc6c6fc20d0a660fb5700dca9ebf51ebe89/src/libcore/fmt/num.rs#L201-L254
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[`fmt::Formatter`]: https://doc.rust-lang.org/std/fmt/struct.Formatter.html
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[`dtoa`]: https://github.com/dtolnay/dtoa
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```toml
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[dependencies]
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itoa = "0.4"
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```
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## Performance (lower is better)
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## Examples
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```rust
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use std::{fmt, io};
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fn demo_itoa_write() -> io::Result<()> {
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// Write to a vector or other io::Write.
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let mut buf = Vec::new();
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itoa::write(&mut buf, 128u64)?;
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println!("{:?}", buf);
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// Write to a stack buffer.
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let mut bytes = [0u8; 20];
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let n = itoa::write(&mut bytes[..], 128u64)?;
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println!("{:?}", &bytes[..n]);
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Ok(())
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}
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fn demo_itoa_fmt() -> fmt::Result {
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// Write to a string.
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let mut s = String::new();
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itoa::fmt(&mut s, 128u64)?;
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println!("{}", s);
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Ok(())
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}
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```
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The function signatures are:
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```rust
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fn write<W: io::Write, V: itoa::Integer>(writer: W, value: V) -> io::Result<usize>;
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fn fmt<W: fmt::Write, V: itoa::Integer>(writer: W, value: V) -> fmt::Result;
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```
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where `itoa::Integer` is implemented for `i8`, `u8`, `i16`, `u16`, `i32`, `u32`,
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`i64`, `u64`, `i128`, `u128`, `isize` and `usize`. 128-bit integer support is
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only available with the nightly compiler when the `i128` feature is enabled for
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this crate. The return value gives the number of bytes written.
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The `write` function is only available when the `std` feature is enabled
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(default is enabled).
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<br>
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#### License
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<sup>
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Licensed under either of <a href="LICENSE-APACHE">Apache License, Version
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2.0</a> or <a href="LICENSE-MIT">MIT license</a> at your option.
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</sup>
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<br>
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<sub>
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Unless you explicitly state otherwise, any contribution intentionally submitted
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for inclusion in this crate by you, as defined in the Apache-2.0 license, shall
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be dual licensed as above, without any additional terms or conditions.
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</sub>
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