commit | 1b4c50fd894a0e753031651c2371fa5497eb2db9 | [log] [tgz] |
---|---|---|
author | Xin Li <delphij@google.com> | Sat Feb 20 00:24:19 2021 -0800 |
committer | Xin Li <delphij@google.com> | Sat Feb 20 00:24:19 2021 -0800 |
tree | 8deaebfc1ab9a7bc9d72e464f128e72c9d84e7e2 | |
parent | b4ad162358877cc1d9d9b65d57818f904734d47c [diff] | |
parent | c31a8529d4db5db36b4d9748a2152ba8cda743a7 [diff] |
Mark ab/7061308 as merged in stage. Bug: 180401296 Merged-In: Ifa41cf173d0d5517dcb3ee794d27581200e85f58 Change-Id: I6a95826397c098ba94026a7aabe20afbf6f37315
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.