Slices in Zig

A slice is a pointer plus a length onto memory that already exists.

const std = @import("std");

pub fn main() void {
    var week = [_]i32{ 61, 68, 74, 79, 72, 65, 58 };

    // A slice is a pointer plus a length onto existing memory.
    const midweek: []i32 = week[2..5];
    std.debug.print("midweek: {any}\n", .{midweek});
    std.debug.print("len {d}, first {d}\n", .{ midweek.len, midweek[0] });

    // Writing through the slice writes the array underneath.
    midweek[0] += 1;
    std.debug.print("warmed wednesday: {d}\n", .{week[2]});
}

How it works

1. week[2..5] borrows three days of the array as []i32.
2. .len travels with the slice; indexing is bounds-checked in safe builds.
3. Writing midweek[0] writes the array underneath — same bytes, two names.

Keywords and builtins used here

• const
• fn
• i32
• pub
• var
• void

The run, in numbers

Lines

14

Characters to type

448

Tokens

127

Three-star pace

70 tpm

At the three-star pace of 70 tokens a minute, this run takes about 109 seconds.

Type this snippet

Step 3 of 3 in Optionals & pointers, step 12 of 27 in Language basics.

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Slices in other languages

• Go
• Rust