Internationalization

%n$ conversion specifications

Earlier we noted that the %n$ form of conversion specification lets you convert the nth argument in a printf or scanf argument list rather than the next unused argument. We showed you how you could use the feature to control the format of the date and time in different locales, and suggested that %n$ had a wider
application than that. What we had in mind were cases in which the rules of a given language were built into print statements such as

   printf("%s %s\n",
   	func == MAP ? "Can't map" : "Can't create", pathname);

The problem with this code is that it assumes that the verb precedes the object of the sentence, which is not the case in many languages. In other words, even if we rewrote the fragment to use gettxt, and stored translations of the strings in message files in the appropriate locales, we would still want to use the %n$ conversion specification to switch the arguments to printf depending on the locale. That is, the printf format string

   "%1$s %2$s\n"

in an English-language locale would be written

   "%2$s %1$s\n"

in a locale in which the object of the sentence precedes the predicate.