Arrays

An array type contains its length and element type:

var ports: [3]Int = {80, 443, 8080};

[3]Int and [4]Int are different types. Every element must have a compatible type.

Read and write elements

Array indices start at zero:

var values: [3]Int = {10, 20, 30};
var first = values[0];
values[2] = 40;

An index must have an integer type.

Declare before filling

var results: [3]Int;
results[0] = 12;
results[1] = 24;
results[2] = 48;

This form initializes the array with the element type’s default value before the assignments.

Nested arrays

var grid: [2][3]Int = {
    {1, 2, 3},
    {4, 5, 6}
};

grid[1][0] = 9;

Read the type from left to right: grid contains two arrays, each containing three integers.

Iterate over an array

var values: [4]Int = {2, 4, 6, 8};
var total = 0;

for value in values {
    total = total + value;
}

Use a C-style loop when the index itself is needed:

for var index: Int = 0; index < 4; index = index + 1 {
    println(toString(values[index]));
}

Arrays and slices

A fixed array owns its storage. A slice []T is a view over a sequence and carries a runtime length. Variadic parameters also appear as slices inside the function.

std/slice provides checked helpers such as at, setAt, first, and last. For a collection whose size changes, use List<T>.