Arrays - rust-course

In Rust, an array is defined with a type and a fixed size. Arrays are stored on the stack memory (see Stack), and thus must be used with reasonable sizes. It provides few methods (see Table 1 and array), but can be coerced to slices, which provide most of the interesting methods (see Table 2).

Table 1:Some methods of array

Method	Description
`each_mut()`	Returns an array of mutable references on elements.
`each_ref()`	Returns an array of references on elements.
`map(f)`	Applies function `f()` on each element of the array and returns an array of the same size.

Here is an array of four i32 integers:

let a = [1, 2, 3, 4];
a

[1, 2, 3, 4]

If we want to specify another integer type, we need also to specify the array size:

let a: [i16; 3] = [-8, 4, 6];
a

[-8, 4, 6]

We may construct an array using the repetition of a value:

let a = [4/*value*/; 3/*Number of repetition*/];
a

[4, 4, 4]

Accessing a value is done using the indexing operator []:

let a = [1, 2, 3, 4];
a[2]

3

Any type whose size is known at compile time may be used to build an array. Here is a table of booleans:

let a = [true, false, false];
a

[true, false, false]

A table of floats:

let a = [1.5, -45.23, 10.3];
a

[1.5, -45.23, 10.3]

A table of strings:

let a = ["a", "ab", "abc"];
a

["a", "ab", "abc"]

And a table of tuples:

let a = [(1, 4), (-10, 18)];
a

[(1, 4), (-10, 18)]

Note that all tuples must be similar (i.e.: same element types, same number of elements), otherwise compilation will fail:

let a = [(1, 4), (-10, 18, 4)];
a

[E0308] Error: mismatched types
   ╭─[ command_10:1:1 ]
   │
 1 │ let a = [(1, 4), (-10, 18, 4)];
   │                  ──────┬─────  
   │                        ╰─────── expected a tuple with 2 elements, found one with 3 elements
───╯

8.2 Arrays