redhat man page for abs

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);

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 function.

RETURN VALUE
       Returns the absolute value of the integer argument, of the appropriate integer type for the function.

CONFORMING TO
       SVID 3, POSIX.1, BSD 4.3, ISO/IEC 9899 (C99).  POSIX.1 (1996 edition) only requires the	abs()  function.   ISO/IEC  9899:1990  (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 builtin functions.  GCC 3.0 also handles llabs() and imaxabs() as builtins.

SEE ALSO
       ceil(3), floor(3), fabs(3), rint(3)

GNU
								    2000-12-17								    ABS(3)