HP-UX Reference (11i v1 00/12) - 5 Miscellaneous Topics, 7 Device (Special) Files, 9 General Information, Index (vol 9)

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STANDARD Printed by: Nora Chuang [nchuang] STANDARD
/build/1111/BRICK/man5/!!!intro.5
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s
stdsyms(5) stdsyms(5)
NAME
stdsyms - description of HP-UX header file organization
DESCRIPTION
HP-UX header files are organized in a manner that allows for only a subset of the symbols available in that
header file to be visible to an application that conforms to a specific standard. The ANSI-C, POSIX.1,
POSIX.2, and XPG4 standards each reserve a certain set of symbols for that standard’s namespace. In
addition, the HP-UX implementation of XPG3 and the "OSF AES/OS" provides for a clean namespace
although this is not a specific requirement of those standards.
The following rules apply in determining what symbols are reserved for any standard. These symbols are
reserved for the standard and for use by the implementation, and must be either avoided altogether, or
used exactly as defined by the specified standard.
• All symbols defined by the desired standard are reserved. Refer to the appropriate standards docu-
mentation for a complete list of reserved symbols.
• All symbols beginning with an underscore followed by another underscore or an uppercase letter
are reserved for the implementation.
• All external identifiers beginning with an underscore are reserved for the implementation.
The following is a list of feature test macros which must be defined to obtain the appropriate namespace
from the header files.
_ _STDC_ _
This symbol is automatically defined by the ANSI-C pre-processor
(/opt/langtools/lib/cpp.ansi
) and is automatically defined when specifying an
ANSI-C compile (
cc -Aa). Using the strict ANSI option -Aa requests a pure ANSI-C
namespace, which is the smallest subset of the HP-UX namespace available. The -Aa
option also enables the inclusion of ANSI-C-style function prototypes for increased type
checking. Note that the default namespace when using the -Aa option is the ANSI-C
namespace; therefore a broader namespace must be requested if it is desired.
_POSIX_SOURCE
As documented in the IEEE POSIX.1 standard, the programmer is required to define the
_POSIX_SOURCE feature test macro to obtain the POSIX.1 namespace and POSIX.1 func-
tionality. This feature test macro can be defined, either by using compiler options (-
D_POSIX_SOURCE
) or by using
#define directives in the source files before any
#include directives. Note that the default POSIX namespace is the POSIX.1-1990
namespace. It is necessary to define the
_POSIX1_1988 feature test macro in addition
to the _POSIX_SOURCE macro in order to obtain the POSIX.1-1988 namespace.
_POSIX_C_SOURCE
As documented in the IEEE POSIX.2 standard, the programmer is required to define the
_POSIX_C_SOURCE feature test macro with a value of 2 to obtain the POSIX.1 and
POSIX.2 namespaces and functionality. This feature test macro can be defined, either by
using compiler options (-D_POSIX_C_SOURCE=2) or by using #define directives in
the source files before any #include directives. This macro is also automatically defined
in the XPG4 X/Open namespace (that is, whenever _XOPEN_SOURCE
and _XPG4 are
defined without defining
_XPG2 or _XPG3).
_XOPEN_SOURCE
As documented in the XPG3 and XPG4 standards, the programmer is required to define the
_XOPEN_SOURCE feature test macro to obtain X/Open functionality. This feature test
macro can be defined, either by using compiler options (-D_XOPEN_SOURCE) or by using
#define directives in the source files before any #include directives. Although XPG3
does not specify any namespace pollution rules, XPG4 has instituted such rules. Therefore,
the HP-UX operating system provides clean namespaces whenever _XOPEN_SOURCE is
defined.
The current default X/Open namespace is that corresponding to XPG3. To request other
versions of the X/Open namespace, define _XPG2 or _XPG4 in conjunction with
_XOPEN_SOURCE .
_AES_SOURCE
As documented in the "OSF AES/OS" standard, the programmer is required to define the
_AES_SOURCE feature test macro to obtain OSF functionality. This feature test macro
Section 5−−348 − 1 − HP-UX Release 11i: December 2000
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