HPUX stdsyms[5]
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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.
o All symbols defined by the desired standard are reserved.
Refer to the appropriate standards documentation for a
complete list of reserved symbols.
o All symbols beginning with an underscore followed by another
underscore or an uppercase letter are reserved for the
implementation.
o 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 (/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 functionality. This feature test macro can be
defined, either by using compiler options (-
D_POSIX_SOURCE) or by using #define directives in the
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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 can be defined, either by using
compiler options (-D_AES_SOURCE) or by using #define
directives in the source files before any #include
directives. Although the AES does not specify any
namespace pollution rules, the other standards have
instituted such rules. Therefore HP-UX provideds a
clean namespace whenever _AES_SOURCE is defined.
_HPUX_SOURCE
The programmer can define the _HPUX_SOURCE feature test
macro to obtain the HP-UX namespace and complete HP-UX
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functionality. Note that the HP-UX namespace is
currently a superset of all of the above mentioned
namespaces. When using the compatibility-mode compiler
(cc(1) without the -Aa option) or the C++ compiler, the
HP-UX namespace is provided by default. The programmer
must request one of the other namespaces as described
above to obtain the appropriate subset of the HP-UX
namespace. When using the strict ANSI-C-mode compiler
(cc -Aa), the programmer must specifically request a
broader namespace.
The _HPUX_SOURCE feature test macro can be defined,
either by using compiler options (-D_HPUX_SOURCE) or by
using #define directives in the source files before any
#include directives.
The following is a list of miscellaneous feature test macros that
provide various additional features.
__cplusplus
This symbol is automatically defined by the C++
compiler. Defining this macro enables the ANSI-C-style
function prototypes for increased type checking. Note
that the C++ standard does not specify a namespace;
thus the default namespace for C++ is the HP-UX
namespace (_HPUX_SOURCE).
_POSIX1_1988
This feature test macro should be defined when the
POSIX.1-1988 namespace is required. It should be used
in conjunction with the _POSIX_SOURCE macro if the
default POSIX.1-1990 namespace is not desired.
This macro is defined automatically whenever
_AES_SOURCE or _XPG3 is requested.
_XPG2 The _XPG2 macro can be defined when using the
compatibility-mode compiler to obtain XPG2
functionality. This provides XPG2 specified function
declarations and macros in the HP-UX namespace. Note
that the values obtained from most of the macros
available when using this option are now available at
run-time via the pathconf(), fpathconf(), and sysconf()
system calls (see pathconf(2) and sysconf(2)). Use of
the _XPG2 macro is strongly discouraged because it
gives access to obsolete functionality. Note that no
function prototypes are provided when using this
feature test macro.
_XPG3 The _XPG3 feature test macro is defined automatically
if the programmer has requested the XPG3 namespace
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(i.e., defined _XOPEN_SOURCE, but not some other
conflicting namespace such as _XPG2 or _XPG4).
_XPG4 The _XPG4 feature test macro is provided so that the
programmer can obtain the XPG4 namespace, since it
differs slightly from the _XPG3 namespace. In order to
obtain the XPG4 namespace, the programmer must define
both the _XOPEN_SOURCE and _XPG4 feature test macros.
The _XOPEN_SOURCE and _XPG4 feature test macros can be
defined, either by using compiler options (-
D_XOPEN_SOURCE -D_XPG4) or by using #define directives
in the source files before any #include directives.
_SVID2 The _SVID2 macro can be defined when using the
compatibility mode compiler to obtain SVID2 function
return types in the HP-UX namespace. The default
return types of many functions have since been changed
in the HP-UX operating system to align with the ANSI C,
POSIX, X/Open, and OSF standards.
_CLASSIC_TYPES
The _CLASSIC_TYPES macro can be defined by the
programmer to obtain pre-7.0 style function return
types and structure element types. This macro has been
provided only as a transition aid when migrating from
the pre-7.0 version of HP-UX to standards-based HP-UX.
Use of this macro is strongly discouraged as this
functionality will be removed in a future release of
HP-UX. Note that no function protoytpes are provided
when using this feature test macro.
SEE ALSO
cc(1), cpp(1), pathconf(2), sysconf(2).
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