mirror of https://github.com/mkerrisk/man-pages
123 lines
3.3 KiB
Groff
123 lines
3.3 KiB
Groff
.\" Copyright 1993 David Metcalfe (david@prism.demon.co.uk)
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.\"
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.\" Permission is granted to make and distribute verbatim copies of this
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.\" manual provided the copyright notice and this permission notice are
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.\" preserved on all copies.
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.\"
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.\" Permission is granted to copy and distribute modified versions of this
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.\" manual under the conditions for verbatim copying, provided that the
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.\" entire resulting derived work is distributed under the terms of a
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.\" permission notice identical to this one.
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.\"
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.\" Since the Linux kernel and libraries are constantly changing, this
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.\" manual page may be incorrect or out-of-date. The author(s) assume no
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.\" responsibility for errors or omissions, or for damages resulting from
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.\" the use of the information contained herein. The author(s) may not
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.\" have taken the same level of care in the production of this manual,
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.\" which is licensed free of charge, as they might when working
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.\" professionally.
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.\"
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.\" Formatted or processed versions of this manual, if unaccompanied by
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.\" the source, must acknowledge the copyright and authors of this work.
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.\"
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.\" References consulted:
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.\" Linux libc source code
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.\" Lewine's _POSIX Programmer's Guide_ (O'Reilly & Associates, 1991)
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.\" 386BSD man pages
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.\" Modified Mon Mar 29 22:31:13 1993, David Metcalfe
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.\" Modified Sun Jun 6 23:27:50 1993, David Metcalfe
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.\" Modified Sat Jul 24 21:45:37 1993, Rik Faith (faith@cs.unc.edu)
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.\" Modified Sat Dec 16 15:02:59 2000, Joseph S. Myers
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.\"
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.TH ABS 3 2007-07-26 "GNU" "Linux Programmer's Manual"
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.SH NAME
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abs, labs, llabs, imaxabs \- compute the absolute value of an integer
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.SH SYNOPSIS
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.nf
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.B #include <stdlib.h>
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.sp
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.BI "int abs(int " j );
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.br
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.BI "long int labs(long int " j );
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.br
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.BI "long long int llabs(long long int " j );
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.sp
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.B #include <inttypes.h>
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.sp
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.BI "intmax_t imaxabs(intmax_t " j );
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.fi
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.sp
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.in -4n
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Feature Test Macro Requirements for glibc (see
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.BR feature_test_macros (7)):
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.in
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.sp
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.BR llabs ():
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_XOPEN_SOURCE\ >=\ 600 || _ISOC99_SOURCE; or
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.I cc\ -std=c99
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.SH DESCRIPTION
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The
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.BR abs ()
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function computes the absolute value of the integer
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argument \fIj\fP.
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The
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.BR labs (),
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.BR llabs ()
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and
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.BR imaxabs ()
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functions compute the absolute value of the argument \fIj\fP of the
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appropriate integer type for the function.
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.SH "RETURN VALUE"
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Returns the absolute value of the integer argument, of the appropriate
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integer type for the function.
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.SH "CONFORMING TO"
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SVr4, POSIX.1-2001, 4.3BSD, C99.
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.\" POSIX.1 (1996 edition) only requires the
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.\" .BR abs ()
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.\" function.
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C89 only
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includes the
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.BR abs ()
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and
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.BR labs ()
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functions; the functions
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.BR llabs ()
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and
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.BR imaxabs ()
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were added in C99.
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.SH NOTES
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Trying to take the absolute value of the most negative integer
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is not defined.
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.PP
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The
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.BR llabs ()
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function is included in glibc since version 2.0, but
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is not in libc5 or libc4.
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The
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.BR imaxabs ()
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function is included in
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glibc since version 2.1.1.
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.PP
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For
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.BR llabs ()
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to be declared, it may be necessary to define
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\fB_ISOC99_SOURCE\fP or \fB_ISOC9X_SOURCE\fP (depending on the
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version of glibc) before including any standard headers.
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.PP
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GCC handles
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.BR abs ()
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and
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.BR labs ()
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as built-in functions.
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GCC 3.0 also handles
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.BR llabs ()
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and
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.BR imaxabs ()
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as built-ins.
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.SH "SEE ALSO"
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.BR cabs (3),
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.BR ceil (3),
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.BR fabs (3),
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.BR floor (3),
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.BR rint (3)
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