How do I sort a vector of Strings alphabetically?

Question

I want to order a Strings vector alphabetically

fn main() {
    let mut vec = Vec::new();
    vec.push("richard");
    vec.push("charles");
    vec.push("Peter");
    println!("{:?}", vec);
}

I tried println!("{:?}", vec.sort()); and println!("{}", vec.sort_by(|a,b| b.cmp(a))); and both response is ().

And I expect the following result

["charles", "Peter", "richard"]

Hi I tried ```println!("{:?}", vec.sort());``` and ```println!("{}", vec.sort_by(|a,b| b.cmp(a)));``` and both response is ```()``` — Ricardo Prieto, Apr 22 '19 at 03:33
The response () is because the sort method modifies the vector itself. — Svetlin Zarev, Apr 22 '19 at 05:08
Thanks for your answer @SvetlinZarev , I'm new in Rust, the question can be very silly. — Ricardo Prieto, Apr 22 '19 at 05:28

score 29 · Accepted Answer · answered Apr 22 '19 at 04:24

sort function is defined on slices (and on Vecs, as they can Deref to slices) as pub fn sort(&mut self), i.e. it performs sorting in place, mutating the existing piece of data. So to achieve what you're trying to do, you can try the following:

fn main() {
    let mut vec = Vec::new();
    vec.push("richard");
    vec.push("charles");
    vec.push("Peter");
    vec.sort();
    println!("{:?}", vec);
}

Unhappily, this isn't quite the thing you want, since this will sort "Peter" before "charles" - the default comparator of strings is case-sensitive (in fact, it's even locale-agnostic, since it compares basing on Unicode code points). So, if you want to perform case-insensitive sorting, here's the modification:

fn main() {
    let mut vec = Vec::new();
    vec.push("richard");
    vec.push("charles");
    vec.push("Peter");
    vec.sort_by(|a, b| a.to_lowercase().cmp(&b.to_lowercase()));
    println!("{:?}", vec);
}

The line that does the sorting could be more concisely replaced by `vec.sort_by_key(|name| name.to_lowercase());` — asky, Aug 15 '21 at 03:20

How do I sort a vector of Strings alphabetically?

1 Answers1