Mastering Rust - Second Edition

Slicing and dicing strings

All strings in Rust are guaranteed to be UTF-8 by default, and indexing on string types in Rust does not work as you would use them in other languages. Let's try accessing the individual characters of our string:

// strings_indexing.rsfn main() {    let hello = String::from("Hello");    let first_char = hello[0];}

On compiling this, we get the following error:

That's not a very helpful message. But it refers to something called the Index trait. The Index trait is implemented on collection types whose elements can be accessed by the indexing operator [] using index type as a usize value. Strings are valid UTF-8-encoded ...