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[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  2000-12-17 "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
.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 "CONFORMING TO"
SVr4, POSIX.1-2001, 4.3BSD, C99.
.\" POSIX.1 (1996 edition) only requires 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, but
is not in libc5 or libc4.
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
GCC handles
.BR abs ()
and
.BR labs ()
as builtin functions.
GCC 3.0 also handles
.BR llabs ()
and
.BR imaxabs ()
as builtins.
.SH "SEE ALSO"
.BR cabs (3),
.BR ceil (3),
.BR fabs (3),
.BR floor (3),
.BR rint (3)