How do I concatenate two slices in Rust?

Question

I want to take the x first and last elements from a vector and concatenate them. I have the following code:

fn main() {     let v = (0u64 .. 10).collect::<Vec<_>>();     let l = v.len();     vec![v.iter().take(3), v.iter().skip(l-3)]; } 

This gives me the error

error[E0308]: mismatched types  --> <anon>:4:28   | 4 |     vec![v.iter().take(3), v.iter().skip(l-3)];   |                            ^^^^^^^^^^^^^^^^^^ expected struct `std::iter::Take`, found struct `std::iter::Skip` <anon>:4:5: 4:48 note: in this expansion of vec! (defined in <std macros>)   |   = note: expected type `std::iter::Take<std::slice::Iter<'_, u64>>`   = note:    found type `std::iter::Skip<std::slice::Iter<'_, u64>>` 

How do I get my vec of 1, 2, 3, 8, 9, 10? I am using Rust 1.12.

Answer 1

Just use .concat() on a slice of slices:

fn main() {     let v = (0u64 .. 10).collect::<Vec<_>>();     let l = v.len();     let first_and_last = [&v[..3], &v[l - 3..]].concat();     println!("{:?}", first_and_last);     // The output is `[0, 1, 2, 7, 8, 9]` } 

This creates a new vector, and it works with arbitrary number of slices.

(Playground link)