| .\" Copyright 1993 David Metcalfe (david@prism.demon.co.uk) |
| .\" |
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| .\" Since the Linux kernel and libraries are constantly changing, this |
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| .\" References consulted: |
| .\" Linux libc source code |
| .\" Lewine's _POSIX Programmer's Guide_ (O'Reilly & Associates, 1991) |
| .\" 386BSD man pages |
| .\" Modified Mon Mar 29 22:31:13 1993, David Metcalfe |
| .\" Modified Sun Jun 6 23:27:50 1993, David Metcalfe |
| .\" Modified Sat Jul 24 21:45:37 1993, Rik Faith (faith@cs.unc.edu) |
| .\" Modified Sat Dec 16 15:02:59 2000, Joseph S. Myers |
| .\" |
| .TH ABS 3 2021-03-22 "GNU" "Linux Programmer's Manual" |
| .SH NAME |
| abs, labs, llabs, imaxabs \- compute the absolute value of an integer |
| .SH SYNOPSIS |
| .nf |
| .B #include <stdlib.h> |
| .PP |
| .BI "int abs(int " j ); |
| .BI "long labs(long " j ); |
| .BI "long long llabs(long long " j ); |
| .PP |
| .B #include <inttypes.h> |
| .PP |
| .BI "intmax_t imaxabs(intmax_t " j ); |
| .fi |
| .PP |
| .RS -4 |
| Feature Test Macro Requirements for glibc (see |
| .BR feature_test_macros (7)): |
| .RE |
| .PP |
| .BR llabs (): |
| .nf |
| _ISOC99_SOURCE || _POSIX_C_SOURCE >= 200112L |
| .fi |
| .SH DESCRIPTION |
| The |
| .BR abs () |
| function computes the absolute value of the integer |
| argument \fIj\fP. |
| The |
| .BR labs (), |
| .BR llabs (), |
| and |
| .BR imaxabs () |
| functions compute the absolute value of the argument \fIj\fP of the |
| appropriate integer type for the function. |
| .SH RETURN VALUE |
| Returns the absolute value of the integer argument, of the appropriate |
| integer type for the function. |
| .SH ATTRIBUTES |
| For an explanation of the terms used in this section, see |
| .BR attributes (7). |
| .ad l |
| .nh |
| .TS |
| allbox; |
| lbx lb lb |
| l l l. |
| Interface Attribute Value |
| T{ |
| .BR abs (), |
| .BR labs (), |
| .BR llabs (), |
| .BR imaxabs () |
| T} Thread safety MT-Safe |
| .TE |
| .hy |
| .ad |
| .sp 1 |
| .SH CONFORMING TO |
| POSIX.1-2001, POSIX.1-2008, C99, SVr4, 4.3BSD. |
| .\" POSIX.1 (1996 edition) requires only the |
| .\" .BR abs () |
| .\" function. |
| C89 only |
| includes the |
| .BR abs () |
| and |
| .BR labs () |
| functions; the functions |
| .BR llabs () |
| and |
| .BR imaxabs () |
| were added in C99. |
| .SH NOTES |
| Trying to take the absolute value of the most negative integer |
| is not defined. |
| .PP |
| The |
| .BR llabs () |
| function is included in glibc since version 2.0. |
| The |
| .BR imaxabs () |
| function is included in |
| glibc since version 2.1.1. |
| .PP |
| For |
| .BR llabs () |
| to be declared, it may be necessary to define |
| \fB_ISOC99_SOURCE\fP or \fB_ISOC9X_SOURCE\fP (depending on the |
| version of glibc) before including any standard headers. |
| .PP |
| By default, |
| GCC handles |
| .BR abs (), |
| .BR labs (), |
| and (since GCC 3.0) |
| .BR llabs () |
| and |
| .BR imaxabs () |
| as built-in functions. |
| .SH SEE ALSO |
| .BR cabs (3), |
| .BR ceil (3), |
| .BR fabs (3), |
| .BR floor (3), |
| .BR rint (3) |