commit | 146b1583a22a77e95823509a5d161b55e7f587da | [log] [tgz] |
---|---|---|
author | Daniel Norman <danielnorman@google.com> | Mon Feb 08 11:11:03 2021 -0800 |
committer | Daniel Norman <danielnorman@google.com> | Mon Feb 08 11:11:03 2021 -0800 |
tree | fcbd51b8adf2d2ed89cee6ccad95ba1a594992eb | |
parent | 6c27bcc9bdff32ba79e5f4346bbe3f9087c0351b [diff] | |
parent | a513a5b014481e4c9cf4aa2d8c067d672e39e2c4 [diff] |
Merge SP1A.210208.001 Change-Id: I304a51600656280f3495997e1fa07f16c9833064
This crate provides fast functions for printing integer primitives to an io::Write
or a fmt::Write
. The implementation comes straight from libcore but avoids the performance penalty of going through fmt::Formatter
.
See also dtoa
for printing floating point primitives.
Version requirement: rustc 1.0+
[dependencies] itoa = "0.4"
use std::{fmt, io}; fn demo_itoa_write() -> io::Result<()> { // 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 = [0u8; 20]; let n = itoa::write(&mut bytes[..], 128u64)?; println!("{:?}", &bytes[..n]); Ok(()) } fn demo_itoa_fmt() -> fmt::Result { // Write to a string. let mut s = String::new(); itoa::fmt(&mut s, 128u64)?; println!("{}", s); Ok(()) }
The function signatures are:
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 requires rustc 1.26+ and the i128
feature of this crate enabled.
The write
function is only available when the std
feature is enabled (default is enabled). The return value gives the number of bytes written.