Zig Cheat Sheet

Core Zig syntax covering variables, error unions, control flow, structs, and compile-time features for systems programming.

2 PagesAdvancedMar 22, 2026

Basics

Variables and formatted printing.

zig

const std = @import("std");pub fn main() void {    std.debug.print("Hello, {s}!\n", .{"World"});    const x: i32 = 42;       // const = immutable    var y: i32 = 10;         // var = mutable    y += 1;    std.debug.print("x={d}, y={d}\n", .{ x, y });}

Error Handling

Error unions, catch, and try.

zig

const std = @import("std");const MyError = error{ NotFound, OutOfRange };fn getItem(index: usize) MyError!i32 {    if (index > 10) return MyError.OutOfRange;    return 42;}pub fn main() void {    const value = getItem(3) catch |err| {        std.debug.print("error: {}\n", .{err});        return;    };    std.debug.print("value: {d}\n", .{value});    // try propagates the error to the caller:    // const v = try getItem(3);}

Control Flow

Branching, looping, and scope-exit cleanup.

if (cond) { } else { }- Standard conditional expression/statement
while (cond) { }- Loop while a condition holds
for (items) |item| { }- Iterate over a slice or array
switch (x) { 1 => ..., else => ... }- Pattern-based branching
defer cleanup();- Runs cleanup when the current scope exits
orelse- Provides a default when unwrapping an optional (?T)

Structs & Types

Custom types and Zig-specific type constructs.

const Point = struct { x: f32, y: f32 };- Defines a struct type
?T- Optional type, either a T value or null
!T- Error union, either an error or a T value
[]const u8- String slice (byte slice), Zig's idiomatic string type
comptime- Marks a value or code evaluated at compile time
std.ArrayList(T)- Growable dynamic array from the standard library

Pro Tip

Use defer right after acquiring a resource (allocation, file open) so cleanup code lives next to the acquisition — it always runs, even on early returns or errors.

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