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ABS(3)                     Linux Programmer's Manual                    ABS(3)

NAME
       abs, labs, llabs, imaxabs - compute the absolute value of an integer
SYNOPSIS
       #include <stdlib.h>
       int abs(int j);
       long int labs(long int j);
       long long int llabs(long long int j);
       #include <inttypes.h>
       intmax_t imaxabs(intmax_t j);
   Feature Test Macro Requirements for glibc (see feature_test_macros(7)):
       llabs():
           _XOPEN_SOURCE >= 600 || _ISOC99_SOURCE ||
           _POSIX_C_SOURCE >= 200112L;
           or cc -std=c99
DESCRIPTION
       The abs() function computes the absolute value of the integer  argument
       j.   The  labs(),  llabs() and imaxabs() functions compute the absolute
       value of the argument j of the appropriate integer type for  the  func-
       tion.
RETURN VALUE
       Returns  the absolute value of the integer argument, of the appropriate
       integer type for the function.
ATTRIBUTES
   Multithreading (see pthreads(7))
       The abs(), labs(), llabs(), and imaxabs() functions are thread-safe.
CONFORMING TO
       SVr4, POSIX.1-2001, 4.3BSD, C99.   C89  only  includes  the  abs()  and
       labs()  functions;  the  functions  llabs() and imaxabs() were added in
       C99.
NOTES
       Trying to take the absolute value of the most negative integer  is  not
       defined.
       The llabs() function is included in glibc since version 2.0, but is not
       in libc5 or libc4.  The imaxabs() function is included in  glibc  since
       version 2.1.1.
       For   llabs()   to   be   declared,  it  may  be  necessary  to  define
       _ISOC99_SOURCE or _ISOC9X_SOURCE (depending on the  version  of  glibc)
       before including any standard headers.
       GCC  handles abs() and labs() as built-in functions.  GCC 3.0 also han-
       dles llabs() and imaxabs() as built-ins.
SEE ALSO
       cabs(3), ceil(3), fabs(3), floor(3), rint(3)
COLOPHON
       This page is part of release 3.53 of the Linux  man-pages  project.   A
       description  of  the project, and information about reporting bugs, can
       be found at http://www.kernel.org/doc/man-pages/.

GNU                               2013-06-21                            ABS(3)