An array is a collection of objects of the same type T, stored in contiguous
memory. Arrays are created using brackets [], and their size, which is known
at compile time, is part of their type signature [T; size].
Slices are similar to arrays, but their size is not known at compile time.
Instead, a slice is a two-word object, the first word is a pointer to the data,
and the second word is the length of the slice. Slices can be used to borrow a
section of an array, and have the type signature &[T].
use std::mem;
// This function borrows a slice
fn analyze_slice(slice: &[i32]) {
println!("first element of the slice: {}", slice[0]);
println!("the slice has {} elements", slice.len());
}
fn main() {
// Fixed-size array (type signature is superfluous)
let xs: [i32; 5] = [1, 2, 3, 4, 5];
// All elements can be initialized to the same value
let ys: [i32; 500] = [0; 500];
// Indexing starts at 0
println!("first element of the array: {}", xs[0]);
println!("second element of the array: {}", xs[1]);
// `len` returns the size of the array
println!("array size: {}", xs.len());
// Arrays are stack allocated
println!("array occupies {} bytes", mem::size_of_val(&xs));
// Arrays can be automatically borrowed as slices
println!("borrow the whole array as a slice");
analyze_slice(&xs);
// Slices can point to a section of an array
println!("borrow a section of the array as a slice");
analyze_slice(&ys[1 .. 4]);
// Out of bound indexing yields a panic
println!("{}", xs[5]);
}