GENWiki

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():
         _ISOC99_SOURCE || _POSIX_C_SOURCE >= 200112L

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

     For   an   explanation   of   the  terms  used  in  this  section,  see
     attributes(7).

     +-------------------+---------------+---------+
     |Interface          | Attribute     | Value   |
     +-------------------+---------------+---------+
     |abs(), labs(),     | Thread safety | MT-Safe |
     |llabs(), imaxabs() |               |         |
     +-------------------+---------------+---------+

CONFORMING TO

     POSIX.1-2001,  POSIX.1-2008,  C99, SVr4, 4.3BSD.  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.  The imax-
     abs() 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.

     By  default, GCC handles abs(), labs(), and (since GCC 3.0) llabs() and
     imaxabs() as built-in functions.