ROUND(3P) POSIX Programmer's Manual ROUND(3P)PROLOG
This manual page is part of the POSIX Programmer's Manual. The Linux
implementation of this interface may differ (consult the corresponding
Linux manual page for details of Linux behavior), or the interface may
not be implemented on Linux.
NAME
round, roundf, roundl — round to the nearest integer value in a float‐
ing-point format
SYNOPSIS
#include <math.h>
double round(double x);
float roundf(float x);
long double roundl(long double x);
DESCRIPTION
The functionality described on this reference page is aligned with the
ISO C standard. Any conflict between the requirements described here
and the ISO C standard is unintentional. This volume of POSIX.1‐2008
defers to the ISO C standard.
These functions shall round their argument to the nearest integer value
in floating-point format, rounding halfway cases away from zero,
regardless of the current rounding direction.
RETURN VALUE
Upon successful completion, these functions shall return the rounded
integer value. The result shall have the same sign as x.
If x is NaN, a NaN shall be returned.
If x is ±0 or ±Inf, x shall be returned.
ERRORS
No errors are defined.
The following sections are informative.
EXAMPLES
None.
APPLICATION USAGE
The integral value returned by these functions need not be expressible
as an intmax_t. The return value should be tested before assigning it
to an integer type to avoid the undefined results of an integer over‐
flow.
These functions may raise the inexact floating-point exception if the
result differs in value from the argument.
RATIONALE
None.
FUTURE DIRECTIONS
None.
SEE ALSOfeclearexcept(), fetestexcept()
The Base Definitions volume of POSIX.1‐2008, Section 4.19, Treatment of
Error Conditions for Mathematical Functions, <math.h>
COPYRIGHT
Portions of this text are reprinted and reproduced in electronic form
from IEEE Std 1003.1, 2013 Edition, Standard for Information Technology
-- Portable Operating System Interface (POSIX), The Open Group Base
Specifications Issue 7, Copyright (C) 2013 by the Institute of Electri‐
cal and Electronics Engineers, Inc and The Open Group. (This is
POSIX.1-2008 with the 2013 Technical Corrigendum 1 applied.) In the
event of any discrepancy between this version and the original IEEE and
The Open Group Standard, the original IEEE and The Open Group Standard
is the referee document. The original Standard can be obtained online
at http://www.unix.org/online.html .
Any typographical or formatting errors that appear in this page are
most likely to have been introduced during the conversion of the source
files to man page format. To report such errors, see https://www.ker‐
nel.org/doc/man-pages/reporting_bugs.html .
IEEE/The Open Group 2013 ROUND(3P)
