Center Rust string in a number of characters

Question

I have been reading up on format! and all of the formatting options and saw there was a beautiful way of centering a string of text using either <, ^ or >. Rather than centering a string in whitespace, is it possible to center it in a character?

{:^32} // Centers it nicely in 32 characters of whitespace

I was thinking something like:

{:^32'c'} // But this does not work

I have tried almost every way thinkable, except those that seem way too crazy. But luckily there is Stack Overflow!

Is it possible to center a string using numbers to achieve something like the following?

--------SO is AWESOME--------

Answer 1

Is it possible to center a string using numbers to achieve something like the following?

Yes, kind of, as long as you truly mean "something like"...

fn main() {
    let s = format!("{:-^30}", "SO is AWESOME");
    assert_eq!(s, "--------SO is AWESOME---------");
    //             ^-- 8 here           ^-- 9 here
}

Referring to the formatting syntax, here's the relevant parts:

format_spec := [[fill]align][sign]['#']['0'][width]['.' precision][type]
fill := character
align := '<' | '^' | '>'
width := count

We specify a fill (-), an alignment (^ / center), and a width (30). However, the string is 13 units wide, so to pad it out to 30 units, the fill has to be bigger on one side.