The nl_langinfo() function shall return a pointer to a string containing
information relevant to the particular language or cultural area defined in
the program's locale (see <langinfo.h>). The manifest constant
names and values of item are defined in <langinfo.h>. For
would return a pointer to the string "Dom" if the identified
language was Portuguese, and "Sun" if the identified language
Calls to setlocale() with a category corresponding to the category of
item (see <langinfo.h>), or to the category LC_ALL, may overwrite the array pointed to by the return value.
The nl_langinfo() function need not be reentrant. A function that is not
required to be reentrant is not required to be thread-safe.
In a locale where langinfo data is not defined, nl_langinfo()
shall return a pointer to the corresponding string in the POSIX locale. In all
locales, nl_langinfo() shall return a pointer to an empty string if
item contains an invalid setting.
This pointer may point to static data that may be overwritten on the next call.
Portions of this text are reprinted and reproduced in electronic form from IEEE
Std 1003.1, 2003 Edition, Standard for Information Technology -- Portable
Operating System Interface (POSIX), The Open Group Base Specifications Issue
6, Copyright (C) 2001-2003 by the Institute of Electrical and Electronics
Engineers, Inc and The Open Group. In the event of any discrepancy between
this version and the original IEEE and The Open Group Standard, the original
IEEE and The Open Group Standard is the referee document. The original
Standard can be obtained online at http://www.opengroup.org/unix/online.html