Mark strings for translation

Before the strings from your application can be translated, they need to be extracted from the source code.

Wrap messages or string literals in your code with the '_()' macro.

For C, this macro is defined in the glib/gi18n.h header file, which must be included at the top of your application source.

Your wrapped strings should look like this:

_("Press a key to continue")

This marks the strings as translatable, and at runtime calls gettext to substitute the translated strings.