Raw string literalLiteral

Explanation

A raw string literal disables escape processing entirely — every character between the quotes is taken literally, including backslashes, as in r"C:\Users\name" or a regex pattern like r"\d+\.\d+".

When the string itself needs to contain a ", wrap it in matching # delimiters — r#"..."# — and use as many # as needed to avoid ambiguity with any # sequences inside the content itself (r##"contains "# inside"##). Like a normal string literal, the result type is &str; the only difference is how the literal's source text is interpreted, not the resulting type.

Usage examples

Representing a Windows-style file path

let path = r"C:\temp\file"; // <- `r"..."`: raw string, backslashes are literal, not escapes

Restriction: # delimiters must be balanced and matched — r#"..."# needs the same number of # on both sides, chosen high enough to avoid ambiguity with any # sequences in the content.

Working with text

A Windows path written as a normal string literal needs every backslash doubled — a raw string sidesteps that entirely.

// AVOID: every backslash must be doubled, easy to miscount
let escaped = "C:\\Users\\alice\\AppData\\config.toml";

// PREFER: raw string, backslashes are literal, no escaping needed
let path = r"C:\Users\alice\AppData\config.toml"; // <- raw string literal: backslashes taken literally

assert_eq!(escaped, path);

A raw string removes the need to double every backslash, which for a Windows path or a regex pattern (r"\d+\.\d+") quickly becomes hard to both write correctly and review; see string literal for the general escape-processing rules a raw string opts out of.

Explanation

Embedded support: Full

A raw string is unaffected by #![no_std] in exactly the same way an ordinary string literal is — it's still &'static str rodata, resolved entirely at compile time, no allocator involved. There isn't much genuinely new to say for embedded specifically: the backslash-heavy content a raw string is built for — regex patterns, Windows-style paths — shows up on the host-tooling side of embedded work (build scripts, flashing utilities, config parsers) more often than in on-target firmware code, which tends to deal in byte buffers rather than backslash-laden text. Where it does help on-target is the same readability win as on desktop: a fixed pattern or path string with several backslashes is easier to write and review without doubling each one.

Usage examples

A path constant for a host-side firmware-flashing tool

// AVOID: every backslash must be doubled, easy to miscount
let firmware_dir = "C:\\Users\\dev\\firmware\\builds";

// PREFER: raw string, backslashes are literal, no escaping needed
let firmware_dir = r"C:\Users\dev\firmware\builds"; // <- raw string literal: backslashes taken literally

assert_eq!(firmware_dir.len(), 27);