I created a simple QLabel with a tr (instead of a plain QString)

I then used Qt Linguist to translate the ts file: very easy! The hardest part was how to launch qt linguist. I expected Qt Creator to propose it, but couldn't find that. I located the tool at ~/Qt/6.0.3/gcc_64/bin/linguist (using find command).

Then modified main.cpp to install a translator, and voilà !

I'm going to show how to do add translation for Spanish for example:

1. Register a new translation file in CMakeLists.txt

set(TS_FILES
  translations/QtInternationalization_fr_FR.ts
+ translations/QtInternationalization_es_ES.ts
)

Now build again. That file will be created.

Note: this is better than actually copying the French one because that way Qt linguist will show you in the UI what you haven't translated yet.

2. Open qt linguist. You can load both translation files at the same time to get more context. Add your translation, save with Ctrl + Enter

You can see PR#2 for the actual code changes I did.

After building, you can launch the executable by passing LANG= env variable

# Default to your current locale, english in my case
./QtInternationalization
LANG=fr_CA.UTF-8 ./QtInternationalization
LANG=fr_FR.UTF-8 ./QtInternationalization
LANG=es_ES.UTF-8 ./QtInternationalization