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This post is auto-generated from RSS feed The Rust Programming Language Forum - Latest topics. Source: Simplify the call to from_be_bytes?

I'm reading data from a fingerprint scanner, and it have different size packages depending on what command it was sent..
The simpler ones are:

let start = u16::from_be_bytes([self.buffer[0], self.buffer[1]]);

However, this is really getting out of hand:

                    fpm_model: u128::from_be_bytes([
                        self.buffer[10],
                        self.buffer[11],
                        self.buffer[12],
                        self.buffer[13],
                        self.buffer[14],
                        self.buffer[15],
                        self.buffer[16],
                        self.buffer[17],
                        self.buffer[18],
                        self.buffer[19],
                        self.buffer[20],
                        self.buffer[21],
                        self.buffer[22],
                        self.buffer[23],
                        self.buffer[24],
                        self.buffer[25],
                    ]),

Looking through examples, this should be possible:

let start = u16::from_be_bytes(self.buffer[0..1].try_into().unwrap());

which would making the retrieval of that FPM model real easy:

fpm_model = u128::from_be_bytes(self.buffer[10..25].try_into().unwrap());

The code would be soooo simpler, easier to read, and more importantly, easier to write . Because I have quite a number of those big ones left to do..

However, that first one gives me a panic! It compiles fine, but then panics:

called `Result::unwrap()` on an `Err` value: TryFromSliceError(())

The buffer variable is defined in my constructor as:

buffer: heapless::Vec::new()

I've gone over the heapless::Vec, slices, vec's and whatever else docs I could find, but can't find anything that seem .. resonable and usable.

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