rustc_data_structures/thousands/
mod.rs

1//! This is a bare-bones alternative to the `thousands` crate on crates.io, for
2//! printing large numbers in a readable fashion.
3
4#[cfg(test)]
5mod tests;
6
7fn format_with_underscores(mut s: String) -> String {
8    // Ignore a leading '-'.
9    let start = if s.starts_with('-') { 1 } else { 0 };
10
11    // Stop after the first non-digit, e.g. '.' or 'e' for floats.
12    let non_digit = s[start..].find(|c: char| !c.is_digit(10));
13    let end = if let Some(non_digit) = non_digit { start + non_digit } else { s.len() };
14
15    // Insert underscores within `start..end`.
16    let mut i = end;
17    while i > start + 3 {
18        i -= 3;
19        s.insert(i, '_');
20    }
21    s
22}
23
24/// Print a `usize` with underscore separators.
25pub fn usize_with_underscores(n: usize) -> String {
26    format_with_underscores(format!("{n}"))
27}
28
29/// Print an `isize` with underscore separators.
30pub fn isize_with_underscores(n: isize) -> String {
31    format_with_underscores(format!("{n}"))
32}
33
34/// Print an `f64` with precision 1 (one decimal place) and underscore separators.
35pub fn f64p1_with_underscores(n: f64) -> String {
36    format_with_underscores(format!("{n:.1}"))
37}
rustc_data_structures/thousands/mod.rs

rustc_data_structures/thousands/
mod.rs
