@cindex library
The GNU C library, described in this document, defines all of the
-library functions that are specified by the ANSI C standard, as well as
+library functions that are specified by the @w{ISO C} standard, as well as
additional features specific to POSIX and other derivatives of the Unix
operating system, and extensions specific to the GNU system.
This manual is written with the assumption that you are at least
somewhat familiar with the C programming language and basic programming
-concepts. Specifically, familiarity with ANSI standard C
-(@pxref{ANSI C}), rather than ``traditional'' pre-ANSI C dialects, is
+concepts. Specifically, familiarity with ISO standard C
+(@pxref{ISO C}), rather than ``traditional'' pre-ISO C dialects, is
assumed.
The GNU C library includes several @dfn{header files}, each of which
@cindex standards
This section discusses the various standards and other sources that the
-GNU C library is based upon. These sources include the ANSI C and
+GNU C library is based upon. These sources include the @w{ISO C} and
POSIX standards, and the System V and Berkeley Unix implementations.
The primary focus of this manual is to tell you how to make effective
standards each function or symbol comes from.
@menu
-* ANSI C:: The American National Standard for the
- C programming language.
-* POSIX:: The IEEE 1003 standards for operating
- systems.
+* ISO C:: The international standard for the C
+ programming language.
+* POSIX:: The ISO/IEC 9945 (aka IEEE 1003) standards
+ for operating systems.
* Berkeley Unix:: BSD and SunOS.
* SVID:: The System V Interface Description.
@end menu
-@node ANSI C, POSIX, , Standards and Portability
-@subsection ANSI C
-@cindex ANSI C
+@node ISO C, POSIX, , Standards and Portability
+@subsection ISO C
+@cindex ISO C
The GNU C library is compatible with the C standard adopted by the
American National Standards Institute (ANSI):
-@cite{American National Standard X3.159-1989---``ANSI C''}.
+@cite{American National Standard X3.159-1989---``ANSI C''} and later
+by the International Standardization Organizaion (ISO):
+@cite{ISO/IEC 9899:1990, ``Programming languages---C''}.
+We here refer to the standard as @w{ISO C} since this is the more
+general standard in respect of ratification.
The header files and library facilities that make up the GNU library are
-a superset of those specified by the ANSI C standard.@refill
+a superset of those specified by the @w{ISO C} standard.@refill
@pindex gcc
-If you are concerned about strict adherence to the ANSI C standard, you
+If you are concerned about strict adherence to the @w{ISO C} standard, you
should use the @samp{-ansi} option when you compile your programs with
-the GNU C compiler. This tells the compiler to define @emph{only} ANSI
+the GNU C compiler. This tells the compiler to define @emph{only} ISO
standard features from the library header files, unless you explicitly
ask for additional features. @xref{Feature Test Macros}, for
information on how to do this.
-Being able to restrict the library to include only ANSI C features is
-important because ANSI C puts limitations on what names can be defined
+Being able to restrict the library to include only @w{ISO C} features is
+important because @w{ISO C} puts limitations on what names can be defined
by the library implementation, and the GNU extensions don't fit these
limitations. @xref{Reserved Names}, for more information about these
restrictions.
This manual does not attempt to give you complete details on the
-differences between ANSI C and older dialects. It gives advice on how
+differences between @w{ISO C} and older dialects. It gives advice on how
to write programs to work portably under multiple C dialects, but does
not aim for completeness.
-@node POSIX, Berkeley Unix, ANSI C, Standards and Portability
+@node POSIX, Berkeley Unix, ISO C, Standards and Portability
@subsection POSIX (The Portable Operating System Interface)
@cindex POSIX
@cindex POSIX.1
various versions of the Unix operating system.
The library facilities specified by the POSIX standards are a superset
-of those required by ANSI C; POSIX specifies additional features for
-ANSI C functions, as well as specifying new additional functions. In
+of those required by @w{ISO C}; POSIX specifies additional features for
+@w{ISO C} functions, as well as specifying new additional functions. In
general, the additional requirements and functionality defined by the
POSIX standards are aimed at providing lower-level support for a
particular kind of operating system environment, rather than general
The GNU C library implements all of the functions specified in
@cite{IEEE Std 1003.1-1990, the POSIX System Application Program
Interface}, commonly referred to as POSIX.1. The primary extensions to
-the ANSI C facilities specified by this standard include file system
+the @w{ISO C} facilities specified by this standard include file system
interface primitives (@pxref{File System Interface}), device-specific
terminal control functions (@pxref{Low-Level Terminal Interface}), and
process control functions (@pxref{Processes}).
are not formally standardized, specifically from the 4.2 BSD, 4.3 BSD,
and 4.4 BSD Unix systems (also known as @dfn{Berkeley Unix}) and from
@dfn{SunOS} (a popular 4.2 BSD derivative that includes some Unix System
-V functionality). These systems support most of the ANSI and POSIX
+V functionality). These systems support most of the @w{ISO C} and POSIX
facilities, and 4.4 BSD and newer releases of SunOS in fact support them all.
The BSD facilities include symbolic links (@pxref{Symbolic Links}), the
superset of the POSIX standard (@pxref{POSIX}).
The GNU C library defines some of the facilities required by the SVID
-that are not also required by the ANSI or POSIX standards, for
+that are not also required by the @w{ISO C} or POSIX standards, for
compatibility with System V Unix and other Unix systems (such as
SunOS) which include these facilities. However, many of the more
obscure and less generally useful facilities required by the SVID are
are included doesn't matter.
@strong{Compatibility Note:} Inclusion of standard header files in any
-order and any number of times works in any ANSI C implementation.
+order and any number of times works in any @w{ISO C} implementation.
However, this has traditionally not been the case in many older C
implementations.
@cindex name space
The names of all library types, macros, variables and functions that
-come from the ANSI C standard are reserved unconditionally; your program
+come from the @w{ISO C} standard are reserved unconditionally; your program
@strong{may not} redefine these names. All other library names are
reserved if your program explicitly includes the header file that
defines or declares them. There are several reasons for these
projects / thirdparty / glibc.git / blobdiff