Collections

Arrays

The length of an array must be known at comptime. If that’s not possible, a slice should be used.

Syntax

Type: [len]Type, or with a sentinel: [len:sentinel]Type
Create an array: [_]Type{ a, b, c }
Length: arr.len
Index: arr[idx]
Destructure: const a, const b = [_]i32{ 1, 2 };
Comptime concat: arr1 ++ arr2
Comptime repeat: arr ** int

Cookbook

Standard for-loop

const arr = [_]i32{ 1, 2, 4, 8, 16 };
for (arr) |v| {
    doThings(v);
}

Mutable looping

var arr = [_]i32{ 1, 2, 4, 8, 16 };
for &arr |*v| {
    v.* *= 2;
}

Indexed looping

const arr = [_]i32{ 1, 2, 4, 8, 16 };
for (arr, 0..) |v, i| {
    std.debug.print("Index {d} has {d}\n", .{v, i});
}

Zero initialization

const zeros = [_]i32{0} ** 100;

Strings

String literals are actually constant pointers to a null-terminated array. Since their lengths are always known they can be coerced to slices or a null-temrinated pointer. They can also be converted to the underlying array by dereferencing them.

By convention, since Zig has no string type, functions taking a string use type []const u8.

Vectors

Vectors are like arrays, but they let you run operations in parallel on them using SIMD.

They can hold the following:

Booleans
Integers
Floats
Pointers

They support these operations:

Arithmetic (including complex arithmetic like @sqrt)
Bitwise
Comparison
Boolean not

Using type coercion they can be converted to arrays and back. Using slc.* a slice can be converted to a vector if it’s length is comptime known.

Syntax

Type: @Vector(len, Type)
Create a vector: @Vector(len, Type){ a, b, c, d }
Index: vec[idx]
Destructure: const a, const b = vec;