ABSSection: Linux Programmer's Manual (3)
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NAMEabs, labs, llabs, imaxabs - compute the absolute value of an integer
#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)):
DESCRIPTIONThe 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 VALUEReturns the absolute value of the integer argument, of the appropriate integer type for the function.
CONFORMING TOSVr4, POSIX.1-2001, 4.3BSD, C99. C89 only includes the abs() and labs() functions; the functions llabs() and imaxabs() were added in C99.
NOTESTrying 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.
SEE ALSOcabs(3), ceil(3), fabs(3), floor(3), rint(3)
COLOPHONThis page is part of release 3.21 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/.