a64l.3: CONFORMING TO: add POSIX.1-2008

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

.\" Copyright 1993 David Metcalfe (david@prism.demon.co.uk)
.\"
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.\" 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  2015-03-02 "GNU" "Linux Programmer's Manual"
.SH NAME
abs, labs, llabs, imaxabs \- compute the absolute value of an integer
.SH SYNOPSIS
.nf
.B #include <stdlib.h>
.sp
.BI "int abs(int " j );
.br
.BI "long int labs(long int " j );
.br
.BI "long long int llabs(long long int " j );
.sp
.B #include <inttypes.h>
.sp
.BI "intmax_t imaxabs(intmax_t " j );
.fi
.sp
.in -4n
Feature Test Macro Requirements for glibc (see
.BR feature_test_macros (7)):
.in
.sp
.ad l
.BR llabs ():
.RS 4
_XOPEN_SOURCE\ >=\ 600 || _ISOC99_SOURCE ||
_POSIX_C_SOURCE\ >=\ 200112L;
.br
or
.I cc\ -std=c99
.RE
.ad
.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
.TS
allbox;
lb lb lb
l l l.
Interface	Attribute	Value
T{
.BR abs (),
.BR labs (),
.BR llabs (),
.BR imaxabs ()
T}	Thread safety	MT-Safe
.TE
.ad
.SH CONFORMING TO
SVr4, POSIX.1-2001, 4.3BSD, C99.
.\" 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)