Text

Import std.text to use string extensions, formatting, Unicode views, and regular expressions:

import std.text;

String Operations

let text = "  Feng Language  ";
let trimmed = text.trim();
let lower = trimmed.toLowerCase();
let upper = trimmed.toUpperCase();
let found = trimmed.contains("Language");
let index = trimmed.indexOf("Lang");
let parts = trimmed.split(" ");

Other commonly used methods include startsWith, endsWith, replace, repeat, padStart, padEnd, clone, and toBytes.

string.length() returns the number of UTF-8 bytes. at(index) and getByte(index) also operate on byte positions. Do not use them to count user-visible characters.

Joining and Formatting

let joined = string.join(", ", ["Feng", "C", "LLVM"]);
let message = string.format("{0}: {1}", "score", "100");

Placeholders use zero-based indexes such as {0} and {1}. An invalid or out-of-range placeholder is preserved as written.

Arguments of the same type that satisfy Display can also be formatted directly:

import std.numeric;

let message = string.format<int>("{0} + {1} = {2}", 20, 22, 42);

Unicode Views

Strings are stored as UTF-8. Use a rune view to iterate over Unicode code points and a grapheme view to iterate over user-visible grapheme clusters. Both avoid treating the bytes of a multibyte character as separate text characters.

Regular Expressions

let pattern = RegExp("[0-9]+");
defer {
  pattern.destroy();
}

let matched = pattern.test("Feng 42");
let matches = pattern.findAll("1, 2, 3");
let replaced = pattern.replaceAll("v1 v2", "version");

Use RegExpFlag to configure case sensitivity, multiline mode, dot-all behavior, and related options. RegExp owns native resources, so call destroy() after use and prefer defer to guarantee cleanup.

Strings also provide convenience methods such as matches, replacePattern, and splitPattern.