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Kaan Baha Sever
ENTR, Türkçe oku
Open source

i18n-cpp

A lightweight, header-only C++ internationalization library: translations in plain .properties files, one per language, looked up by key, with named placeholders filled in at run time.

Source code
Fig. 1 A translation lookup: a key is read from the active language’s .properties file, then a named placeholder is filled in at run time.

What it is

i18n-cpp is a small internationalization (i18n) library for C++: it lets an application show its text in the user’s language. It is a single header, so there is nothing to compile or link: include it, load a language and look strings up by key. It is released under the MIT License.

It is small on purpose. It is meant for small and medium-sized applications where a minimal footprint matters; for very large translation files or complex localization needs, established tools such as ICU or gettext are the better fit, and the README says so.

How it works

Translations live in plain .properties files, one folder per language:

locales/
├── en/messages.properties
├── es/messages.properties
└── fr/messages.properties

Each line maps a key to its text (greeting=Hello, World!). Lines that start with # are comments, and whitespace around keys and values is trimmed.

  • I18n::loadLocale("en") reads a language’s file and reports whether it could be opened.
  • I18n::translate(key) returns the text for a key, or an empty string when the key is missing.
  • I18n::interpolate(key, values) fills named placeholders such as {name} from a map of values at run time, so Welcome to our application {name}. becomes Welcome to our application John.
  • Short macros: _t(key) and _f(key, values), or the longer I18N_T and I18N_F, keep call sites short.
#include "i18n/i18n.hpp"

I18n::loadLocale("en");
std::cout << _t("greeting") << '\n';  // Hello, World!
std::cout << _f("personalized_greeting", {{"name", "John"}}) << '\n';

The API is a set of static methods on one class, so there is no object to create or pass around.

Requirements

The header needs nothing beyond the C++ standard library. The repository includes an example program with English, Spanish and French sample files; the example builds with CMake as C++11.

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