Convert Vec to Array with TryFrom

help
1

Hello!

I'm having trouble converting a vector that I know is of size 32 to an array.

Here is some sample playground code that is erroring:

It says the trait bound [T; 32]: std::convert::TryFrom<&[T]> is not satisfied, but that doesn't seem to be right according to this documentation:

I was following this StackOverflow post originally:
https://stackoverflow.com/questions/25428920/how-to-get-a-slice-as-an-array-in-rust

Any help will be much appreciated! Thank you!

2

Solved!

It requires that the type T implement the Copy trait.

fn demo<T>(v: Vec<T>) -> [T; 32] where T: Copy {
    let slice = v.as_slice();
    let array: [T; 32] = match slice.try_into() {
        Ok(ba) => ba,
        Err(_) => panic!("Expected a Vec of length {} but it was {}", 32, v.len()),
    };
    array
}
3

Next release you'll be able to go directly from a Vec<T>, without needing T: Copy: TryFrom in std::convert - Rust

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