CODEWITHSUNDEEP
rust
anthony de meulemeester
anthony de meulemeester

Reputation: 41

Indexing a String

I want to perform a very simple task, but I cannot manage to stop the compiler from complaining.

fn transform(s: String) -> String {
    let bytes = s.as_bytes();
    format!("{}/{}", bytes[0..2], bytes[2..4])
}

[u8] does not have a constant size known at compile-time.

Some tips making this operation to work as intended?

Upvotes: 3

Views: 212

Answers (1)

A.B.
A.B.

Reputation: 16630

Indeed, the size of a [u8] isn't known at compile time. The size of &[u8] however is known at compile time because it's just a pointer plus a usize representing the length of sequence.

format!("{:?}/{:?}", &bytes[0..2], &bytes[2..4])

Rust strings are encoded in utf-8, so working with strings in this way is generally a bad idea because a single unicode character may consist of multiple bytes.

Upvotes: 5

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