Recently I decided to add some translations to my program. I wonder how I should name the language files?

1. in the culture's name of the language (example: english = en, french = fr, italian = it, etc...)

2. in the name of the language [in english] (example: english = english, french = french, italian = italian, etc..)

I know you'll choose the second way because you dont have to detect which filename it is because both have the same name. But the problem is this - I show the name of the languages in its langauge (example: english = english, french = française, italian = italiano, etc..) so I still need to detect which filename it is.

The main question is which way I should choose? the name of the language in english or the culture name? and why?...

Thanks!