ABS(3) Linux Programmer's Manual ABS(3)
abs, labs, llabs, imaxabs - compute the absolute value of an integer
int abs(int j);
long int labs(long int j);
long long int llabs(long long int j);
intmax_t imaxabs(intmax_t j);
Feature Test Macro Requirements for glibc (see feature_test_macros(7)):
_XOPEN_SOURCE >= 600 || _ISOC99_SOURCE || _POSIX_C_SOURCE >= 200112L;
or cc -std=c99
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 appro-
priate integer type for the function.
Returns the absolute value of the integer argument, of the appropriate integer type for
Multithreading (see pthreads(7))
The abs(), labs(), llabs(), and imaxabs() functions are thread-safe.
SVr4, POSIX.1-2001, 4.3BSD, C99. C89 only includes the abs() and labs() functions; the
functions llabs() and imaxabs() were added in C99.
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 handles llabs() and
imaxabs() as built-ins.
cabs(3), ceil(3), fabs(3), floor(3), rint(3)
This page is part of release 3.55 of the Linux man-pages project. A description of the
project, and information about reporting bugs, can be found at
GNU 2013-06-21 ABS(3)