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<!doctype html>
<html lang="en">
<head>
<meta charset="utf-8">
<meta name="viewport" content="width=device-width, initial-scale=1.0">
<title>Documentation - The Zig Programming Language</title>
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<body>
<header><h1>Zig Language Reference</h1></header>
<div id="main-wrapper">
<div id="navigation">
<nav aria-labelledby="zig-version">
<h2 id="zig-version">Zig Version</h2>
<a href="https://ziglang.org/documentation/0.1.1/">0.1.1</a> |
<a href="https://ziglang.org/documentation/0.2.0/">0.2.0</a> |
<a href="https://ziglang.org/documentation/0.3.0/">0.3.0</a> |
<a href="https://ziglang.org/documentation/0.4.0/">0.4.0</a> |
<a href="https://ziglang.org/documentation/0.5.0/">0.5.0</a> |
<a href="https://ziglang.org/documentation/0.6.0/">0.6.0</a> |
<a href="https://ziglang.org/documentation/0.7.1/">0.7.1</a> |
<a href="https://ziglang.org/documentation/0.8.1/">0.8.1</a> |
<a href="https://ziglang.org/documentation/0.9.1/">0.9.1</a> |
<a href="https://ziglang.org/documentation/0.10.1/">0.10.1</a> |
master
</nav>
<nav aria-labelledby="table-of-contents">
<h2 id="table-of-contents">Table of Contents</h2>
{#nav#}
</nav>
</div>
<div id="contents-wrapper"><main id="contents">
{#header_open|Introduction#}
<p>
<a href="https://ziglang.org">Zig</a> is a general-purpose programming language and toolchain for maintaining
<strong>robust</strong>, <strong>optimal</strong>, and <strong>reusable</strong> software.
</p>
<dl>
<dt>Robust</dt><dd>Behavior is correct even for edge cases such as out of memory.</dd>
<dt>Optimal</dt><dd>Write programs the best way they can behave and perform.</dd>
<dt>Reusable</dt><dd>The same code works in many environments which have different
constraints.</dd>
<dt>Maintainable</dt><dd>Precisely communicate intent to the compiler and
other programmers. The language imposes a low overhead to reading code and is
resilient to changing requirements and environments.</dd>
</dl>
<p>
Often the most efficient way to learn something new is to see examples, so
this documentation shows how to use each of Zig's features. It is
all on one page so you can search with your browser's search tool.
</p>
<p>
The code samples in this document are compiled and tested as part of the main test suite of Zig.
</p>
<p>
This HTML document depends on no external files, so you can use it offline.
</p>
{#header_close#}
{#header_open|Zig Standard Library#}
<p>
The <a href="https://ziglang.org/documentation/master/std/">Zig Standard Library</a> has its own documentation.
</p>
<p>
Zig's Standard Library contains commonly used algorithms, data structures, and definitions to help you build programs or libraries.
You will see many examples of Zig's Standard Library used in this documentation. To learn more about the Zig Standard Library,
visit the link above.
</p>
{#header_close#}
{#header_open|Hello World#}
{#code_begin|exe|hello#}
const std = @import("std");
pub fn main() !void {
const stdout = std.io.getStdOut().writer();
try stdout.print("Hello, {s}!\n", .{"world"});
}
{#code_end#}
<p>
The Zig code sample above demonstrates one way to create a program that will output: <samp>Hello, world!</samp>.
</p>
<p>
The code sample shows the contents of a file named <code class="file">hello.zig</code>. Files storing Zig
source code are {#link|UTF-8 encoded|Source Encoding#} text files. The files storing
Zig source code are usually named with the <code class="file"><em>.zig</em></code> extension.
</p>
<p>
Following the <code class="file">hello.zig</code> Zig code sample, the {#link|Zig Build System#} is used
to build an executable program from the <code class="file">hello.zig</code> source code. Then, the
<code class="file">hello</code> program is executed showing its output <samp>Hello, world!</samp>. The
lines beginning with <samp>$</samp> represent command line prompts and a command.
Everything else is program output.
</p>
<p>
The code sample begins by adding the {#link|Zig Standard Library#} to the build using the {#link|@import#} builtin function.
The {#syntax#}@import("std"){#endsyntax#} function call creates a structure that represents the Zig Standard Library.
The code then {#link|declares|Container Level Variables#} a
{#link|constant identifier|Assignment#}, named {#syntax#}std{#endsyntax#}, that gives access to the features of the Zig Standard Library.
</p>
<p>
Next, a {#link|public function|Functions#}, {#syntax#}pub fn{#endsyntax#}, named {#syntax#}main{#endsyntax#}
is declared. The {#syntax#}main{#endsyntax#} function is necessary because it tells the Zig compiler where the start of
the program exists. Programs designed to be executed will need a {#syntax#}pub fn main{#endsyntax#} function.
</p>
<aside role="note" aria-label="Note about main function">
<p>
For more advanced use cases, Zig offers other features to inform the compiler where the start of
the program exists. Also, libraries do not need a {#syntax#}pub fn main{#endsyntax#} function because
library code is called by other programs or libraries.
</p>
</aside>
<p>
A function is a block of any number of statements and expressions that, as a whole, perform a task.
Functions may or may not return data after they are done performing their task. If a function
cannot perform its task, it might return an error. Zig makes all of this explicit.
</p>
<p>
In the <code class="file">hello.zig</code> code sample, the <code>main</code> function is declared
with the {#syntax#}!void{#endsyntax#} return type. This return type is known as an {#link|Error Union Type#}.
This syntax tells the Zig compiler that the function will either return an
error or a value. An error union type combines an {#link|Error Set Type#} and any other data type
(e.g. a {#link|Primitive Type|Primitive Types#} or a user-defined type such as a {#link|struct#}, {#link|enum#}, or {#link|union#}).
The full form of an error union type is
<code><error set type></code>{#syntax#}!{#endsyntax#}<code><any data type></code>. In the code
sample, the error set type is not explicitly written on the left side of the {#syntax#}!{#endsyntax#} operator.
When written this way, the error set type is an {#link|inferred error set type|Inferred Error Sets#}. The
{#syntax#}void{#endsyntax#} after the {#syntax#}!{#endsyntax#} operator
tells the compiler that the function will not return a value under normal circumstances (i.e. when no errors occur).
</p>
<aside role="note" aria-label="Note to disambiguate exclamation mark operator">
<p>
Note to experienced programmers: Zig also has the boolean {#link|operator|Operators#} {#syntax#}!a{#endsyntax#}
where {#syntax#}a{#endsyntax#} is a value of type {#syntax#}bool{#endsyntax#}. Error union types contain the
name of the type in the syntax: {#syntax#}!{#endsyntax#}<code><any data type></code>.
</p>
</aside>
<p>
In Zig, a function's block of statements and expressions are surrounded by an open curly-brace <code>{</code> and
close curly-brace <code>}</code>. Inside of the {#syntax#}main{#endsyntax#} function are expressions that perform
the task of outputting <samp>Hello, world!</samp> to standard output.
</p>
<p>
First, a constant identifier, {#syntax#}stdout{#endsyntax#}, is initialized to represent standard output's
writer. Then, the program tries to print the <samp>Hello, world!</samp>
message to standard output.
</p>
<p>
Functions sometimes need information to perform their task. In Zig, information is passed
to functions between an open parenthesis {#syntax#}({#endsyntax#} and a close parenthesis {#syntax#}){#endsyntax#} placed after
the function's name. This information is also known as arguments. When there are
multiple arguments passed to a function, they are separated by commas {#syntax#},{#endsyntax#}.
</p>
<p>
The two arguments passed to the {#syntax#}stdout.print(){#endsyntax#} function, {#syntax#}"Hello, {s}!\n"{#endsyntax#}
and {#syntax#}.{"world"}{#endsyntax#}, are evaluated at {#link|compile-time|comptime#}. The code sample is
purposely written to show how to perform {#link|string|String Literals and Unicode Code Point Literals#}
substitution in the {#syntax#}print{#endsyntax#} function. The curly-braces inside of the first argument
are substituted with the compile-time known value inside of the second argument
(known as an {#link|tuple|Tuples#}). The <code>\n</code>
inside of the double-quotes of the first argument is the {#link|escape sequence|Escape Sequences#} for the
newline character. The {#link|try#} expression evaluates the result of {#syntax#}stdout.print{#endsyntax#}.
If the result is an error, then the {#syntax#}try{#endsyntax#} expression will return from
{#syntax#}main{#endsyntax#} with the error. Otherwise, the program will continue. In this case, there are no
more statements or expressions left to execute in the {#syntax#}main{#endsyntax#} function, so the program exits.
</p>
<p>
In Zig, the standard output writer's {#syntax#}print{#endsyntax#} function is allowed to fail because
it is actually a function defined as part of a generic Writer. Consider a generic Writer that
represents writing data to a file. When the disk is full, a write to the file will fail.
However, we typically do not expect writing text to the standard output to fail. To avoid having
to handle the failure case of printing to standard output, you can use alternate functions: the
functions in {#syntax#}std.log{#endsyntax#} for proper logging or the {#syntax#}std.debug.print{#endsyntax#} function.
This documentation will use the latter option to print to standard error (stderr) and silently return
on failure. The next code sample, <code class="file">hello_again.zig</code> demonstrates the use of
{#syntax#}std.debug.print{#endsyntax#}.
</p>
{#code_begin|exe|hello_again#}
const print = @import("std").debug.print;
pub fn main() void {
print("Hello, world!\n", .{});
}
{#code_end#}
<p>
Note that you can leave off the {#syntax#}!{#endsyntax#} from the return type because {#syntax#}std.debug.print{#endsyntax#} cannot fail.
</p>
{#see_also|Values|@import|Errors|Root Source File|Source Encoding#}
{#header_close#}
{#header_open|Comments#}
{#code_begin|exe|comments#}
const print = @import("std").debug.print;
pub fn main() void {
// Comments in Zig start with "//" and end at the next LF byte (end of line).
// The line below is a comment and won't be executed.
//print("Hello?", .{});
print("Hello, world!\n", .{}); // another comment
}
{#code_end#}
<p>
There are no multiline comments in Zig (e.g. like <code class="c">/* */</code>
comments in C). This helps allow Zig to have the property that each line
of code can be tokenized out of context.
</p>
{#header_open|Doc comments#}
<p>
A doc comment is one that begins with exactly three slashes (i.e.
{#syntax#}///{#endsyntax#} but not {#syntax#}////{#endsyntax#});
multiple doc comments in a row are merged together to form a multiline
doc comment. The doc comment documents whatever immediately follows it.
</p>
{#code_begin|syntax|doc_comments#}
/// A structure for storing a timestamp, with nanosecond precision (this is a
/// multiline doc comment).
const Timestamp = struct {
/// The number of seconds since the epoch (this is also a doc comment).
seconds: i64, // signed so we can represent pre-1970 (not a doc comment)
/// The number of nanoseconds past the second (doc comment again).
nanos: u32,
/// Returns a `Timestamp` struct representing the Unix epoch; that is, the
/// moment of 1970 Jan 1 00:00:00 UTC (this is a doc comment too).
pub fn unixEpoch() Timestamp {
return Timestamp{
.seconds = 0,
.nanos = 0,
};
}
};
{#code_end#}
<p>
Doc comments are only allowed in certain places; eventually, it will
become a compile error to have a doc comment in an unexpected place, such as
in the middle of an expression, or just before a non-doc comment.
</p>
{#header_close#}
{#header_open|Top-Level Doc Comments#}
<p>User documentation that doesn't belong to whatever
immediately follows it, like {#link|container|Containers#}-level documentation, goes
in top-level doc comments. A top-level doc comment is one that
begins with two slashes and an exclamation point:
{#syntax#}//!{#endsyntax#}.</p>
{#code_begin|syntax|tldoc_comments#}
//! This module provides functions for retrieving the current date and
//! time with varying degrees of precision and accuracy. It does not
//! depend on libc, but will use functions from it if available.
{#code_end#}
{#header_close#}
{#header_close#}
{#header_open|Values#}
{#code_begin|exe|values#}
// Top-level declarations are order-independent:
const print = std.debug.print;
const std = @import("std");
const os = std.os;
const assert = std.debug.assert;
pub fn main() void {
// integers
const one_plus_one: i32 = 1 + 1;
print("1 + 1 = {}\n", .{one_plus_one});
// floats
const seven_div_three: f32 = 7.0 / 3.0;
print("7.0 / 3.0 = {}\n", .{seven_div_three});
// boolean
print("{}\n{}\n{}\n", .{
true and false,
true or false,
!true,
});
// optional
var optional_value: ?[]const u8 = null;
assert(optional_value == null);
print("\noptional 1\ntype: {}\nvalue: {?s}\n", .{
@TypeOf(optional_value), optional_value,
});
optional_value = "hi";
assert(optional_value != null);
print("\noptional 2\ntype: {}\nvalue: {?s}\n", .{
@TypeOf(optional_value), optional_value,
});
// error union
var number_or_error: anyerror!i32 = error.ArgNotFound;
print("\nerror union 1\ntype: {}\nvalue: {!}\n", .{
@TypeOf(number_or_error), number_or_error, });
number_or_error = 1234;
print("\nerror union 2\ntype: {}\nvalue: {!}\n", .{
@TypeOf(number_or_error), number_or_error,
});
}
{#code_end#}
{#header_open|Primitive Types#}
<div class="table-wrapper">
<table>
<caption>Primitive Types</caption>
<thead>
<tr>
<th scope="col">Type</th>
<th scope="col">C Equivalent</th>
<th scope="col">Description</th>
</tr>
</thead>
<tbody>
<tr>
<th scope="row">{#syntax#}i8{#endsyntax#}</th>
<td><code class="c">int8_t</code></td>
<td>signed 8-bit integer</td>
</tr>
<tr>
<th scope="row">{#syntax#}u8{#endsyntax#}</th>
<td><code class="c">uint8_t</code></td>
<td>unsigned 8-bit integer</td>
</tr>
<tr>
<th scope="row">{#syntax#}i16{#endsyntax#}</th>
<td><code class="c">int16_t</code></td>
<td>signed 16-bit integer</td>
</tr>
<tr>
<th scope="row">{#syntax#}u16{#endsyntax#}</th>
<td><code class="c">uint16_t</code></td>
<td>unsigned 16-bit integer</td>
</tr>
<tr>
<th scope="row">{#syntax#}i32{#endsyntax#}</th>
<td><code class="c">int32_t</code></td>
<td>signed 32-bit integer</td>
</tr>
<tr>
<th scope="row">{#syntax#}u32{#endsyntax#}</th>
<td><code class="c">uint32_t</code></td>
<td>unsigned 32-bit integer</td>
</tr>
<tr>
<th scope="row">{#syntax#}i64{#endsyntax#}</th>
<td><code class="c">int64_t</code></td>
<td>signed 64-bit integer</td>
</tr>
<tr>
<th scope="row">{#syntax#}u64{#endsyntax#}</th>
<td><code class="c">uint64_t</code></td>
<td>unsigned 64-bit integer</td>
</tr>
<tr>
<th scope="row">{#syntax#}i128{#endsyntax#}</th>
<td><code class="c">__int128</code></td>
<td>signed 128-bit integer</td>
</tr>
<tr>
<th scope="row">{#syntax#}u128{#endsyntax#}</th>
<td><code class="c">unsigned __int128</code></td>
<td>unsigned 128-bit integer</td>
</tr>
<tr>
<th scope="row">{#syntax#}isize{#endsyntax#}</th>
<td><code class="c">intptr_t</code></td>
<td>signed pointer sized integer</td>
</tr>
<tr>
<th scope="row">{#syntax#}usize{#endsyntax#}</th>
<td><code class="c">uintptr_t</code>, <code class="c">size_t</code></td>
<td>unsigned pointer sized integer. Also see <a href="https://github.com/ziglang/zig/issues/5185">#5185</a></td>
</tr>
<tr>
<th scope="row">{#syntax#}c_short{#endsyntax#}</th>
<td><code class="c">short</code></td>
<td>for ABI compatibility with C</td>
</tr>
<tr>
<th scope="row">{#syntax#}c_ushort{#endsyntax#}</th>
<td><code class="c">unsigned short</code></td>
<td>for ABI compatibility with C</td>
</tr>
<tr>
<th scope="row">{#syntax#}c_int{#endsyntax#}</th>
<td><code class="c">int</code></td>
<td>for ABI compatibility with C</td>
</tr>
<tr>
<th scope="row">{#syntax#}c_uint{#endsyntax#}</th>
<td><code class="c">unsigned int</code></td>
<td>for ABI compatibility with C</td>
</tr>
<tr>
<th scope="row">{#syntax#}c_long{#endsyntax#}</th>
<td><code class="c">long</code></td>
<td>for ABI compatibility with C</td>
</tr>
<tr>
<th scope="row">{#syntax#}c_ulong{#endsyntax#}</th>
<td><code class="c">unsigned long</code></td>
<td>for ABI compatibility with C</td>
</tr>
<tr>
<th scope="row">{#syntax#}c_longlong{#endsyntax#}</th>
<td><code class="c">long long</code></td>
<td>for ABI compatibility with C</td>
</tr>
<tr>
<th scope="row">{#syntax#}c_ulonglong{#endsyntax#}</th>
<td><code class="c">unsigned long long</code></td>
<td>for ABI compatibility with C</td>
</tr>
<tr>
<th scope="row">{#syntax#}c_longdouble{#endsyntax#}</th>
<td><code class="c">long double</code></td>
<td>for ABI compatibility with C</td>
</tr>
<tr>
<th scope="row">{#syntax#}f16{#endsyntax#}</th>
<td><code class="c">_Float16</code></td>
<td>16-bit floating point (10-bit mantissa) IEEE-754-2008 binary16</td>
</tr>
<tr>
<th scope="row">{#syntax#}f32{#endsyntax#}</th>
<td><code class="c">float</code></td>
<td>32-bit floating point (23-bit mantissa) IEEE-754-2008 binary32</td>
</tr>
<tr>
<th scope="row">{#syntax#}f64{#endsyntax#}</th>
<td><code class="c">double</code></td>
<td>64-bit floating point (52-bit mantissa) IEEE-754-2008 binary64</td>
</tr>
<tr>
<th scope="row">{#syntax#}f80{#endsyntax#}</th>
<td><code class="c">double</code></td>
<td>80-bit floating point (64-bit mantissa) IEEE-754-2008 80-bit extended precision</td>
</tr>
<tr>
<th scope="row">{#syntax#}f128{#endsyntax#}</th>
<td><code class="c">_Float128</code></td>
<td>128-bit floating point (112-bit mantissa) IEEE-754-2008 binary128</td>
</tr>
<tr>
<th scope="row">{#syntax#}bool{#endsyntax#}</th>
<td><code class="c">bool</code></td>
<td>{#syntax#}true{#endsyntax#} or {#syntax#}false{#endsyntax#}</td>
</tr>
<tr>
<th scope="row">{#syntax#}anyopaque{#endsyntax#}</th>
<td><code class="c">void</code></td>
<td>Used for type-erased pointers.</td>
</tr>
<tr>
<th scope="row">{#syntax#}void{#endsyntax#}</th>
<td>(none)</td>
<td>Always the value {#syntax#}void{}{#endsyntax#}</td>
</tr>
<tr>
<th scope="row">{#syntax#}noreturn{#endsyntax#}</th>
<td>(none)</td>
<td>the type of {#syntax#}break{#endsyntax#}, {#syntax#}continue{#endsyntax#}, {#syntax#}return{#endsyntax#}, {#syntax#}unreachable{#endsyntax#}, and {#syntax#}while (true) {}{#endsyntax#}</td>
</tr>
<tr>
<th scope="row">{#syntax#}type{#endsyntax#}</th>
<td>(none)</td>
<td>the type of types</td>
</tr>
<tr>
<th scope="row">{#syntax#}anyerror{#endsyntax#}</th>
<td>(none)</td>
<td>an error code</td>
</tr>
<tr>
<th scope="row">{#syntax#}comptime_int{#endsyntax#}</th>
<td>(none)</td>
<td>Only allowed for {#link|comptime#}-known values. The type of integer literals.</td>
</tr>
<tr>
<th scope="row">{#syntax#}comptime_float{#endsyntax#}</th>
<td>(none)</td>
<td>Only allowed for {#link|comptime#}-known values. The type of float literals.</td>
</tr>
</tbody>
</table>
</div>
<p>
In addition to the integer types above, arbitrary bit-width integers can be referenced by using
an identifier of <code>i</code> or <code>u</code> followed by digits. For example, the identifier
{#syntax#}i7{#endsyntax#} refers to a signed 7-bit integer. The maximum allowed bit-width of an
integer type is {#syntax#}65535{#endsyntax#}.
</p>
{#see_also|Integers|Floats|void|Errors|@Type#}
{#header_close#}
{#header_open|Primitive Values#}
<div class="table-wrapper">
<table>
<caption>Primitive Values</caption>
<thead>
<tr>
<th scope="col">Name</th>
<th scope="col">Description</th>
</tr>
</thead>
<tbody>
<tr>
<th scope="row">{#syntax#}true{#endsyntax#} and {#syntax#}false{#endsyntax#}</th>
<td>{#syntax#}bool{#endsyntax#} values</td>
</tr>
<tr>
<th scope="row">{#syntax#}null{#endsyntax#}</th>
<td>used to set an optional type to {#syntax#}null{#endsyntax#}</td>
</tr>
<tr>
<th scope="row">{#syntax#}undefined{#endsyntax#}</th>
<td>used to leave a value unspecified</td>
</tr>
</tbody>
</table>
</div>
{#see_also|Optionals|undefined#}
{#header_close#}
{#header_open|String Literals and Unicode Code Point Literals#}
<p>
String literals are constant single-item {#link|Pointers#} to null-terminated byte arrays.
The type of string literals encodes both the length, and the fact that they are null-terminated,
and thus they can be {#link|coerced|Type Coercion#} to both {#link|Slices#} and
{#link|Null-Terminated Pointers|Sentinel-Terminated Pointers#}.
Dereferencing string literals converts them to {#link|Arrays#}.
</p>
<p>
The encoding of a string in Zig is de-facto assumed to be UTF-8.
Because Zig source code is {#link|UTF-8 encoded|Source Encoding#}, any non-ASCII bytes appearing within a string literal
in source code carry their UTF-8 meaning into the content of the string in the Zig program;
the bytes are not modified by the compiler.
However, it is possible to embed non-UTF-8 bytes into a string literal using <code>\xNN</code> notation.
</p>
<p>
Indexing into a string containing non-ASCII bytes will return individual bytes, whether valid
UTF-8 or not.
The {#link|Zig Standard Library#} provides routines for checking the validity of UTF-8 encoded
strings, accessing their code points and other encoding/decoding related tasks in
{#syntax#}std.unicode{#endsyntax#}.
</p>
<p>
Unicode code point literals have type {#syntax#}comptime_int{#endsyntax#}, the same as
{#link|Integer Literals#}. All {#link|Escape Sequences#} are valid in both string literals
and Unicode code point literals.
</p>
<p>
In many other programming languages, a Unicode code point literal is called a "character literal".
However, there is <a href="https://unicode.org/glossary">no precise technical definition of a "character"</a>
in recent versions of the Unicode specification (as of Unicode 13.0).
In Zig, a Unicode code point literal corresponds to the Unicode definition of a code point.
</p>
{#code_begin|exe|string_literals#}
const print = @import("std").debug.print;
const mem = @import("std").mem; // will be used to compare bytes
pub fn main() void {
const bytes = "hello";
print("{}\n", .{@TypeOf(bytes)}); // *const [5:0]u8
print("{d}\n", .{bytes.len}); // 5
print("{c}\n", .{bytes[1]}); // 'e'
print("{d}\n", .{bytes[5]}); // 0
print("{}\n", .{'e' == '\x65'}); // true
print("{d}\n", .{'\u{1f4a9}'}); // 128169
print("{d}\n", .{'💯'}); // 128175
print("{u}\n", .{'⚡'});
print("{}\n", .{mem.eql(u8, "hello", "h\x65llo")}); // true
print("{}\n", .{mem.eql(u8, "💯", "\xf0\x9f\x92\xaf")}); // also true
const invalid_utf8 = "\xff\xfe"; // non-UTF-8 strings are possible with \xNN notation.
print("0x{x}\n", .{invalid_utf8[1]}); // indexing them returns individual bytes...
print("0x{x}\n", .{"💯"[1]}); // ...as does indexing part-way through non-ASCII characters
}
{#code_end#}
{#see_also|Arrays|Source Encoding#}
{#header_open|Escape Sequences#}
<div class="table-wrapper">
<table>
<caption>Escape Sequences</caption>
<thead>
<tr>
<th scope="col">Escape Sequence</th>
<th scope="col">Name</th>
</tr>
</thead>
<tbody>
<tr>
<th scope="row"><code>\n</code></th>
<td>Newline</td>
</tr>
<tr>
<th scope="row"><code>\r</code></th>
<td>Carriage Return</td>
</tr>
<tr>
<th scope="row"><code>\t</code></th>
<td>Tab</td>
</tr>
<tr>
<th scope="row"><code>\\</code></th>
<td>Backslash</td>
</tr>
<tr>
<th scope="row"><code>\'</code></th>
<td>Single Quote</td>
</tr>
<tr>
<th scope="row"><code>\"</code></th>
<td>Double Quote</td>
</tr>
<tr>
<th scope="row"><code>\xNN</code></th>
<td>hexadecimal 8-bit byte value (2 digits)</td>
</tr>
<tr>
<th scope="row"><code>\u{NNNNNN}</code></th>
<td>hexadecimal Unicode code point UTF-8 encoded (1 or more digits)</td>
</tr>
</tbody>
</table>
</div>
<p>Note that the maximum valid Unicode point is {#syntax#}0x10ffff{#endsyntax#}.</p>
{#header_close#}
{#header_open|Multiline String Literals#}
<p>
Multiline string literals have no escapes and can span across multiple lines.
To start a multiline string literal, use the {#syntax#}\\{#endsyntax#} token. Just like a comment,
the string literal goes until the end of the line. The end of the line is
not included in the string literal.
However, if the next line begins with {#syntax#}\\{#endsyntax#} then a newline is appended and
the string literal continues.
</p>
{#code_begin|syntax|multiline_string_literals#}
const hello_world_in_c =
\\#include <stdio.h>
\\
\\int main(int argc, char **argv) {
\\ printf("hello world\n");
\\ return 0;
\\}
;
{#code_end#}
{#see_also|@embedFile#}
{#header_close#}
{#header_close#}
{#header_open|Assignment#}
<p>Use the {#syntax#}const{#endsyntax#} keyword to assign a value to an identifier:</p>
{#code_begin|exe_build_err|constant_identifier_cannot_change#}
const x = 1234;
fn foo() void {
// It works at file scope as well as inside functions.
const y = 5678;
// Once assigned, an identifier cannot be changed.
y += 1;
}
pub fn main() void {
foo();
}
{#code_end#}
<p>{#syntax#}const{#endsyntax#} applies to all of the bytes that the identifier immediately addresses. {#link|Pointers#} have their own const-ness.</p>