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Chapter 6

LOCALE technology

LOCALE is a basic concept introduced into ISO C (ISO/IEC 9899:1990). The standard is expanded

in 1995 (ISO 9899:1990 Amendment 1:1995). In LOCALE model, the behaviors of some C functions

are dependent on LOCALE environment. LOCALE environment is divided into a few categories

and each of these categories can be set independently using

setlocale()

.

POSIX also determines some standards around i18n. Almost of POSIX and ISO C standards are

included in XPG4 (X/Open Portability Guide) standard and all of them are included in XPG5

standard. Note that XPG5 is included in UNIX specifications version 2. Thus support of XPG5 is

mandatory to obtain Unix brand. In other words, all versions of Unix operating systems support

XPG5.

The merit of using locale technology over hard coding of Unicode is:

  The software can be written encoding independent way. This means that this software can

support all encodings which the OS supports, including 7bit, 8bit, multibyte, stateful, and

stateless encodings such as ASCII, ISO 8859 *, EUC *, ISO 2022 *, Big5, VISCII, TIS 620, UTF 

*, and so on.

  The software will provides a common unified method to configure locale and encoding. This

benefits users. Otherwise, users will have to remember the method to enable UTF 8 mode for

each software. Some softwares need

 u8

switch, other need X resource setting, other need

.foobarrc

file, other need a special environmental variable, other use UTF 8 for default. It

is nonsense!

  The advancement of the OS means the advancement of the software. Thus, you can use new

locale without recompiling your software.

You can read the Unicode support in the Solaris Operating Environment (

http://docs.sun.

com/ab2/coll.651.1/SOLUNICOSUPPT

) whitepapaer and understand the merit of this model.