Fixed-size arrays and the workhorse slice type.

Arrays

An array in Go is a fixed-size sequence of elements of one type. The size is part of the type — [3]int and [4]int are different types, and you cannot use one where the other is expected.

You'll use arrays much less than slices. They're the foundation slices are built on.

Declaring

[...] is a small convenience: you write the elements and the compiler figures out the length.

Arrays are values, not references

When you assign or pass an array, the whole thing is copied:

That's a key difference from C and from Go slices. It's also why we usually prefer slices in practice.

Multidimensional arrays

var grid [3][3]int
grid[1][2] = 5

A [3][3]int is "an array of 3 arrays of 3 ints" — Go has no built-in matrix type, but the syntax is straightforward.

Arrays are comparable

Unlike slices, arrays of the same type can be compared with == and used as map keys:

a := [3]int{1, 2, 3}
b := [3]int{1, 2, 3}
fmt.Println(a == b) // true

m := map[[2]string]int{}    // key is a [2]string array
m[[2]string{"go", "lang"}] = 1