rust - How do I get the first character out of a string?

Question

I want to get the first character of a std::str. The method char_at() is currently unstable, as is String::slice_chars.

I have come up with the following, but it seems excessive to get a single character and not use the rest of the vector:

let text = "hello world!";
let char_vec: Vec<char> = text.chars().collect();
let ch = char_vec[0];

Answer 1

UTF-8 does not define what "character" is so it depends on what you want. In this case, chars are Unicode scalar values, and so the first char of a &str is going to be between one and four bytes.

If you want just the first char, then don't collect into a Vec<char>, just use the iterator:

let text = "hello world!";
let ch = text.chars().next().unwrap();

Alternatively, you can use the iterator's nth method:

let ch = text.chars().nth(0).unwrap();

Bear in mind that elements preceding the index passed to nth will be consumed from the iterator.