[thirdparty/man-pages.git] / man3 / abs.3

.\" Copyright 1993 David Metcalfe (david@prism.demon.co.uk)
.\"
.\" SPDX-License-Identifier: Linux-man-pages-copyleft
.\"
.\" References consulted:
.\"     Linux libc source code
.\"     Lewine's _POSIX Programmer's Guide_ (O'Reilly & Associates, 1991)
.\"     386BSD man pages
.\" Modified Mon Mar 29 22:31:13 1993, David Metcalfe
.\" Modified Sun Jun  6 23:27:50 1993, David Metcalfe
.\" Modified Sat Jul 24 21:45:37 1993, Rik Faith (faith@cs.unc.edu)
.\" Modified Sat Dec 16 15:02:59 2000, Joseph S. Myers
.\"
.TH ABS 3  2021-03-22 "Linux man-pages (unreleased)" "Linux Programmer's Manual"
.SH NAME
abs, labs, llabs, imaxabs \- compute the absolute value of an integer
.SH LIBRARY
Standard C library
.RI ( libc ", " \-lc )
.SH SYNOPSIS
.nf
.B #include <stdlib.h>
.PP
.BI "int abs(int " j );
.BI "long labs(long " j );
.BI "long long llabs(long long " j );
.PP
.B #include <inttypes.h>
.PP
.BI "intmax_t imaxabs(intmax_t " j );
.fi
.PP
.RS -4
Feature Test Macro Requirements for glibc (see
.BR feature_test_macros (7)):
.RE
.PP
.BR llabs ():
.nf
    _ISOC99_SOURCE || _POSIX_C_SOURCE >= 200112L
.fi
.SH DESCRIPTION
The
.BR abs ()
function computes the absolute value of the integer
argument \fIj\fP.
The
.BR labs (),
.BR llabs (),
and
.BR imaxabs ()
functions compute the absolute value of the argument \fIj\fP of the
appropriate integer type for the function.
.SH RETURN VALUE
Returns the absolute value of the integer argument, of the appropriate
integer type for the function.
.SH ATTRIBUTES
For an explanation of the terms used in this section, see
.BR attributes (7).
.ad l
.nh
.TS
allbox;
lbx lb lb
l l l.
Interface	Attribute	Value
T{
.BR abs (),
.BR labs (),
.BR llabs (),
.BR imaxabs ()
T}	Thread safety	MT-Safe
.TE
.hy
.ad
.sp 1
.SH STANDARDS
POSIX.1-2001, POSIX.1-2008, C99, SVr4, 4.3BSD.
.\" POSIX.1 (1996 edition) requires only the
.\" .BR abs ()
.\" function.
C89 only
includes the
.BR abs ()
and
.BR labs ()
functions; the functions
.BR llabs ()
and
.BR imaxabs ()
were added in C99.
.SH NOTES
Trying to take the absolute value of the most negative integer
is not defined.
.PP
The
.BR llabs ()
function is included in glibc since version 2.0.
The
.BR imaxabs ()
function is included in
glibc since version 2.1.1.
.PP
For
.BR llabs ()
to be declared, it may be necessary to define
\fB_ISOC99_SOURCE\fP or \fB_ISOC9X_SOURCE\fP (depending on the
version of glibc) before including any standard headers.
.PP
By default,
GCC handles
.BR abs (),
.BR labs (),
and (since GCC 3.0)
.BR llabs ()
and
.BR imaxabs ()
as built-in functions.
.SH SEE ALSO
.BR cabs (3),
.BR ceil (3),
.BR fabs (3),
.BR floor (3),
.BR rint (3)
Commit	Line	Data
	1	.\" Copyright 1993 David Metcalfe (david@prism.demon.co.uk)
	2	.\"
	3	.\" SPDX-License-Identifier: Linux-man-pages-copyleft
	4	.\"
	5	.\" References consulted:
	6	.\" Linux libc source code
	7	.\" Lewine's _POSIX Programmer's Guide_ (O'Reilly & Associates, 1991)
	8	.\" 386BSD man pages
	9	.\" Modified Mon Mar 29 22:31:13 1993, David Metcalfe
	10	.\" Modified Sun Jun 6 23:27:50 1993, David Metcalfe
	11	.\" Modified Sat Jul 24 21:45:37 1993, Rik Faith (faith@cs.unc.edu)
	12	.\" Modified Sat Dec 16 15:02:59 2000, Joseph S. Myers
	13	.\"
	14	.TH ABS 3 2021-03-22 "Linux man-pages (unreleased)" "Linux Programmer's Manual"
	15	.SH NAME
	16	abs, labs, llabs, imaxabs \- compute the absolute value of an integer
	17	.SH LIBRARY
	18	Standard C library
	19	.RI ( libc ", " \-lc )
	20	.SH SYNOPSIS
	21	.nf
	22	.B #include <stdlib.h>
	23	.PP
	24	.BI "int abs(int " j );
	25	.BI "long labs(long " j );
	26	.BI "long long llabs(long long " j );
	27	.PP
	28	.B #include <inttypes.h>
	29	.PP
	30	.BI "intmax_t imaxabs(intmax_t " j );
	31	.fi
	32	.PP
	33	.RS -4
	34	Feature Test Macro Requirements for glibc (see
	35	.BR feature_test_macros (7)):
	36	.RE
	37	.PP
	38	.BR llabs ():
	39	.nf
	40	_ISOC99_SOURCE \|\| _POSIX_C_SOURCE >= 200112L
	41	.fi
	42	.SH DESCRIPTION
	43	The
	44	.BR abs ()
	45	function computes the absolute value of the integer
	46	argument \fIj\fP.
	47	The
	48	.BR labs (),
	49	.BR llabs (),
	50	and
	51	.BR imaxabs ()
	52	functions compute the absolute value of the argument \fIj\fP of the
	53	appropriate integer type for the function.
	54	.SH RETURN VALUE
	55	Returns the absolute value of the integer argument, of the appropriate
	56	integer type for the function.
	57	.SH ATTRIBUTES
	58	For an explanation of the terms used in this section, see
	59	.BR attributes (7).
	60	.ad l
	61	.nh
	62	.TS
	63	allbox;
	64	lbx lb lb
	65	l l l.
	66	Interface Attribute Value
	67	T{
	68	.BR abs (),
	69	.BR labs (),
	70	.BR llabs (),
	71	.BR imaxabs ()
	72	T} Thread safety MT-Safe
	73	.TE
	74	.hy
	75	.ad
	76	.sp 1
	77	.SH STANDARDS
	78	POSIX.1-2001, POSIX.1-2008, C99, SVr4, 4.3BSD.
	79	.\" POSIX.1 (1996 edition) requires only the
	80	.\" .BR abs ()
	81	.\" function.
	82	C89 only
	83	includes the
	84	.BR abs ()
	85	and
	86	.BR labs ()
	87	functions; the functions
	88	.BR llabs ()
	89	and
	90	.BR imaxabs ()
	91	were added in C99.
	92	.SH NOTES
	93	Trying to take the absolute value of the most negative integer
	94	is not defined.
	95	.PP
	96	The
	97	.BR llabs ()
	98	function is included in glibc since version 2.0.
	99	The
	100	.BR imaxabs ()
	101	function is included in
	102	glibc since version 2.1.1.
	103	.PP
	104	For
	105	.BR llabs ()
	106	to be declared, it may be necessary to define
	107	\fB_ISOC99_SOURCE\fP or \fB_ISOC9X_SOURCE\fP (depending on the
	108	version of glibc) before including any standard headers.
	109	.PP
	110	By default,
	111	GCC handles
	112	.BR abs (),
	113	.BR labs (),
	114	and (since GCC 3.0)
	115	.BR llabs ()
	116	and
	117	.BR imaxabs ()
	118	as built-in functions.
	119	.SH SEE ALSO
	120	.BR cabs (3),
	121	.BR ceil (3),
	122	.BR fabs (3),
	123	.BR floor (3),
	124	.BR rint (3)