Rust crate for converting numbers (integers and floats) to strings with thousands separators.
It is very fast because it uses itoa/dtoa crates with stack allocated strings.
extern crate pretty_toa;
use pretty_toa::ThousandsSep;
fn main() {
let num = 123_4567;
println!("{} => {}", num, num.thousands_sep());
let num = 123_4567.1234567;
println!("{} => {}", num, num.thousands_sep());
}