How to pad left in Rust?

Question

I'm new to Rust and completely lost in the standard library. I do not want to add a crate just for padding. How do I pad left a number with zeroes up to a certain width?

Lets say I have this code and I need the pad_left implementation.

fn main() {
  let i = 5.to_string();

  let padded_i = pad_left(i, 2);
}

Yes it does. We can close this as duplicate – ditoslav Nov 12 '20 at 19:54 — ditoslav, Nov 12 '20 at 19:54

score 3 · Answer 1 · answered Nov 12 '20 at 19:48

3

The Rust Docs has an example of how you could format a number as a string with leading zeroes up to a certain width (5 in this example):

format!("Hello {:05}!", 5); // returns, "Hello 00005!"
format!("Hello {:05}!", -5); // returns, "Hello -0005!"

If you need to print the number, then you can replace the format! macro with print! or println! instead.

answered Nov 12 '20 at 19:48

Brent Pappas

392
3
11

And what if I want to pad a str "a" with 'b's ? – ditoslav Nov 12 '20 at 19:53
See the section directly above the one I linked to in my solution: https://doc.rust-lang.org/std/fmt/#fillalignment – Brent Pappas Nov 12 '20 at 19:56
4

@ditoslav `println!("{:b>5}", "a");` will give you `bbbba` – Jason Nov 12 '20 at 20:06

How to pad left in Rust?

1 Answers1