How do you iterate over a string by character

Question

I have a string and I need to scan for every occurrence of "foo" and read all the text following it until a second ". Since Rust does not have a contains function for strings, I need to iterate by characters scanning for it. How would I do this?

Edit: Rust's &str has a contains() and find() method.

Answer 1

I need to iterate by characters scanning for it.

The .chars() method returns an iterator over characters in a string. e.g.

for c in my_str.chars() { 
    // do something with `c`
}

for (i, c) in my_str.chars().enumerate() {
    // do something with character `c` and index `i`
}

If you are interested in the byte offsets of each char, you can use char_indices.

Look into .peekable(), and use peek() for looking ahead. It's wrapped like this because it supports UTF-8 codepoints instead of being a simple vector of characters.

You could also create a vector of chars and work on it from there, but that's more time and space intensive:

let my_chars: Vec<_> = mystr.chars().collect();