Character classification and character transformation macros are defined in /usr/include/ctype.h. The current Oracle Solaris environment provides a set of ctype macros that support character classification and transformation semantics defined by XPG4. For all XPG4 and XPG4.2 applications to automatically access new macros, one of the following conditions must be met:
_XPG4_CHAR_CLASS is defined.
_XOPEN_SOURCE and _XOPEN_VERSION=4 are defined.
_XOPEN_SOURCE and _XOPEN_SOURCE_EXTENDED=1 are defined.
Corresponding ctype functions also exist. The current Oracle Solaris environment functions also support XPG4 semantics.