Set a locale for string collation routines. This controls alphabetic ordering in strcoll and strxfrm.
LC_CTYPE
Set a locale for the ctype(3) and multibyte(3) functions. This controls recognition of upper and lower case, alphabetic or non-alphabetic characters, and so on.
LC_MESSAGES
Set a locale for message catalogs, see catopen(3) function.
LC_MONETARY
Set a locale for formatting monetary values; this affects the localeconv function.
LC_NUMERIC
Set a locale for formatting numbers. This controls the formatting of decimal points in input and output of floating point numbers in functions such as printf and scanf, as well as values returned by localeconv.
LC_TIME
Set a locale for formatting dates and times using the strftime function.
Only three locales are defined by default, the empty string "" "" " which denotes the native environment, and the "" "C" " and "" "POSIX" " locales, which denote the C language environment. A locale argument of NULL causes setlocale to return the current locale. By default, C programs start in the "" "C" " locale. The only function in the library that sets the locale is setlocale; the locale is never changed as a side effect of some other routine.
