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c.7: Describe more recent C standards

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Also, add some MLINKS and fix some typos.

Reviewed by:	bcr
Differential Revision:	https://reviews.freebsd.org/D28441
This commit is contained in:
Faraz Vahedi 2021-04-18 16:19:33 +02:00 committed by Mateusz Piotrowski
parent f4a54f4333
commit 136f6b6c0c
2 changed files with 222 additions and 40 deletions
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14
share/man/man7/Makefile
View File

@ -8,9 +8,9 @@ MAN= arch.7 \
ascii.7 \
bsd.snmpmod.mk.7 \
build.7 \
c.7 \
clocks.7 \
crypto.7 \
c99.7 \
development.7 \
environ.7 \
ffs.7 \
@ -35,10 +35,14 @@ MAN= arch.7 \
MLINKS= intro.7 miscellaneous.7
MLINKS+= security.7 securelevel.7
MLINKS+= c99.7 c.7
MLINKS+= c99.7 c78.7
MLINKS+= c99.7 c89.7
MLINKS+= c99.7 c90.7
MLINKS+= c.7 c78.7
MLINKS+= c.7 c89.7
MLINKS+= c.7 c90.7
MLINKS+= c.7 c95.7
MLINKS+= c.7 c99.7
MLINKS+= c.7 c11.7
MLINKS+= c.7 c17.7
MLINKS+= c.7 c2x.7
.if ${MK_TESTS} != "no"
ATF= ${SRCTOP}/contrib/atf

248
share/man/man7/c99.7 → share/man/man7/c.7
View File

@ -1,4 +1,5 @@
.\" Copyright (C) 2007, 2010 Gabor Kovesdan. All rights reserved.
.\" Copyright (C) 2021 Faraz Vahedi <kfv@kfv.io>
.\"
.\" Redistribution and use in source and binary forms, with or without
.\" modification, are permitted provided that the following conditions
@ -23,7 +24,7 @@
.\"
.\" $FreeBSD$
.\"
.Dd May 30, 2011
.Dd April 18, 2021
.Dt C 7
.Os
.Sh NAME
@ -31,7 +32,11 @@
.Nm c78 ,
.Nm c89 ,
.Nm c90 ,
.Nm c99
.Nm c95 ,
.Nm c99 ,
.Nm c11 ,
.Nm c17 ,
.Nm c2x
.Nd The C programming language
.Sh DESCRIPTION
C is a general purpose programming language, which has a strong connection
@ -81,12 +86,16 @@ Note, that POSIX is not a C standard, but an operating system standard
and thus is beyond the scope of this manual.
The standards discussed below are all C standards and only cover
the C programming language and the accompanying library.
All listed improvements for each standard edition are taken from the official
standard drafts.
For further details, check the publicly available drafts or
purchase the published standards \(em from either ISO or IEC resources.
.Pp
After the publication of the book mentioned before,
the American National Standards Institute (ANSI) started to work on
standardizing the language, and they announced ANSI X3.159-1989
in 1989.
It is usually referred as ANSI C or C89.
It is usually referred to as ANSI C or C89.
The main difference in this standard were the function prototypes,
which is a new way of declaring functions.
With the old-style function declarations, the compiler was unable to
@ -97,54 +106,127 @@ at run-time.
.Pp
In 1990, the International Organization for Standardization (ISO) adopted
the ANSI standard as ISO/IEC 9899:1990 in 1990.
This is also referred as ISO C or C90.
This is also referred to as ISO C or C90.
It only contains negligible minor modifications against ANSI C,
so the two standards often considered to be fully equivalent.
This was a very important milestone in the history of the C language, but the
development of the language did not stop.
.Pp
The ISO C standard was later extended with an amendment as
ISO/IEC 9899 AM1 in 1995.
This contained, for example, the wide-character support in wchar.h and
wctype.h.
Two corrigenda were also published: Technical Corrigendum 1 as
ISO/IEC 9899 TCOR1 in 1995 and Technical Corrigendum 2 as ISO/IEC 9899 TCOR1
ISO/IEC 9899/AMD1 in 1995.
This contained, for example, the wide-character support in <wchar.h> and
<wctype.h>, and also restricted character set support via diagraphs and
<iso646.h>.
This amendment is usually referred to as C95.
Two technical corrigenda were also published: Technical Corrigendum 1 as
ISO/IEC 9899/COR1 in 1994 and Technical Corrigendum 2 as ISO/IEC 9899/COR2
in 1996.
The continuous development and growth made it necessary to work out a new
standard, which contains the new features and fixes the known defects and
deficiencies of the language.
As a result, ISO/IEC 9899:1999 was born in 1999.
Similarly to the other standards, this is referred after the
As a result, ISO/IEC 9899:1999 was born in 1999 as the second edition of the
standard.
Similarly to the other standards, this is informally named after the
publication year as C99.
The improvements include the following:
The improvements include (but are not limited to) the following:
.Bl -bullet -offset indent
.It
Inline functions
digraphs, trigraphs, and alternative spellings for the operators that
use non-ISO646 characters in <iso646.h>
.It
Support for variable length arrays
extended multibyte and wide character library support in <wchar.h> and
<wctype.h>
.It
New high-precision integer type named long long int, and other integer types
defined in stdint.h
variable length arrays
.It
New boolean data type implemented in stdbool.h
flexible array members
.It
One line comments taken from the C++ language
complex (and imaginary) number arithmetic support in <complex.h>
.It
Some new preprocessor features
type-generic math macros in <tgmath.h>
.It
New variables can be declared anywhere, not just in the beginning of the
program or program blocks
the long long int type and library functions
.It
No implicit int type
remove implicit int type
.It
universal character names (\eu and \eU)
.It
compound literals
.It
remove implicit function declaration
.It
BCPL style single-line comments
.It
allow mixed declarations and code
.It
the vscanf family of functions in <stdio.h> and <wchar.h>
.It
allow trailing comma in enum declaration
.It
inline functions
.It
the snprintf family of functions in <stdio.h>
.It
boolean type and macros in <stdbool.h>
.It
empty macro arguments
.It
_Pragma preprocessing operator
.It
__func__ predefined identifier
.It
va_copy macro in <stdarg.h>
.It
additional strftime conversion specifiers
.El
.Pp
Since then new standards have not been published, but the C language is still
evolving.
New and useful features have been showed up in the most famous
C compiler: GNU C.
Most of the UNIX-like operating systems use GNU C as a system compiler,
but those addition in GNU C should not be considered as
standard features.
Later in 2011, the third edition of the standard, ISO/IEC 1989:2011,
commonly reffered to as C11 (formerly C1x), came out and replaced the
second edition by ISO/IEC 9899:1999/COR1:2001, ISO/IEC 9899:1999/COR2:2004,
and ISO/IEC 9899:1999/COR3:2007.
The improvements include (but are not limited to) the following:
.Bl -bullet -offset indent
.It
support for multiple threads of execution and atomic operations in <threads.h>
and <stdatomic.h>
.It
additional floating-point characteristic macros in <float.h>
.It
querying and specifying alignment of objects in <stdalign.h> and <stdlib.h>
.It
Unicode character types and functions in <uchar.h>
.It
type-generic expressions
.It
static assertions in <assert.h>
.It
anonymous structures and unions
.It
remove the gets function from <stdio.h>
.It
add the aligned_alloc, at_quick_exit, and quick_exit functions in <stdlib.h>
.El
.Pp
C11 was later superseded by ISO/IEC 9899:2018, also known as C17 which was
prepared in 2017 and published in June 2018 as the fourth edition.
It incorporates the Technical Corrigendum 1 (ISO/IEC 9899:2011/COR1:2012)
which was published in 2012.
It addressed defects and deficiencies in C11 without introducing new features,
only corrections and clarifications.
Since there were no major changes in C17, the current standrad for
Programming Language C, is still considered C11 \(em ISO/IEC 9899:2011, published
2011-12-08.
.Pp
The next standard, the fifth, is currently referred to as C2x and is scheduled
to be adopted by the end of 2021, with a publication date of 2022.
When published, it will cancel and replace the fourth edition, ISO/IEC
9899:2018.
.Pp
Some useful features have been provided as extensions by some compilers, but
they cannot be considered as standard features.
.Pp
ISO/IEC JTC1/SC22/WG14 committee is responsible for the ISO/IEC 9899,
C Standard.
.Sh SEE ALSO
.Xr c89 1 ,
.Xr c99 1 ,
@ -152,36 +234,132 @@ standard features.
.Sh STANDARDS
.Rs
.%A ANSI
.%T X3.159-1989
.%T X3.159-1989 (aka C89 or ANSI C)
.Re
.Pp
.Rs
.%A ISO/IEC
.%T 9899:1990, Programming languages -- C
.%T 9899:1990 (aka C90)
.Re
.Pp
.Rs
.%A ISO/IEC
.%T 9899 AM1
.%T 9899:1990/AMD 1:1995, Amendment 1: C Integrity (aka C95)
.Re
.Pp
.Rs
.%A ISO/IEC
.%T 9899 TCOR1, Programming languages -- C, Technical Corrigendum 1
.%T 9899:1990/COR 1:1994, Technical Corrigendum 1
.Re
.Pp
.Rs
.%A ISO/IEC
.%T 9899 TCOR2, Programming languages -- C, Technical Corrigendum 2
.%T 9899:1990/COR 2:1996, Technical Corrigendum 2
.Re
.Pp
.Rs
.%A ISO/IEC
.%T 9899:1999, Programming languages -- C
.%T 9899:1999 (aka C99)
.Re
.Pp
.Rs
.%A ISO/IEC
.%T 9899:1999/COR 1:2001, Technical Corrigendum 1
.Re
.Pp
.Rs
.%A ISO/IEC
.%T 9899:1999/COR 2:2004, Technical Corrigendum 2
.Re
.Pp
.Rs
.%A ISO/IEC
.%T 9899:1999/COR 3:2007, Technical Corrigendum 3
.Re
.Pp
.Rs
.%A ISO/IEC
.%T TR 24731-1:2007 (aka bounds-checking interfaces)
.Re
.Pp
.Rs
.%A ISO/IEC
.%T TS 18037:2008 (aka, embedded C)
.Re
.Pp
.Rs
.%A ISO/IEC
.%T TR 24747:2009 (aka mathematical special functions)
.Re
.Pp
.Rs
.%A ISO/IEC
.%T TR 24732:2009 (aka decimal floating-point)
.Re
.Pp
.Rs
.%A ISO/IEC
.%T TR 24731-2:2010 (aka dynamic allocation functions)
.Re
.Pp
.Rs
.%A ISO/IEC
.%T 9899:2011 (aka C11)
.Re
.Pp
.Rs
.%A ISO/IEC
.%T 9899:2011/COR 1:2012, Technical Corrigendum 1
.Re
.Pp
.Rs
.%A ISO/IEC
.%T TS 17961:2013 (aka C secure coding rules)
.Re
.Pp
.Rs
.%A ISO/IEC
.%T TS 18861-1:2014 (aka binary floating-point)
.Re
.Pp
.Rs
.%A ISO/IEC
.%T TS 18861-2:2015 (aka decimal floating-point)
.Re
.Pp
.Rs
.%A ISO/IEC
.%T TS 18861-3:2015 (aka interchange and extended types)
.Re
.Pp
.Rs
.%A ISO/IEC
.%T TS 18861-4:2015 (aka supplementary functions)
.Re
.Pp
.Rs
.%A ISO/IEC
.%T TS 17961:2013/COR 1:2016 (aka C secure coding rules TC1)
.Re
.Pp
.Rs
.%A ISO/IEC
.%T TS 18861-5:2016 (aka supplementary attributes)
.Re
.Pp
.Rs
.%A ISO/IEC
.%T 9899:2018 (aka C17)
.Re
.Sh HISTORY
This manual page first appeared in
.Fx 9.0 .
.Sh AUTHORS
.An -nosplit
This manual page was originally written by
.An Gabor Kovesdan Aq Mt gabor@FreeBSD.org .
It was updated for
.Fx 14.0
by
.An Faraz Vahedi Aq Mt kfv@kfv.io
with information about more recent C standards.