round, roundf, roundl - round to nearest integer, away
from zero
SYNOPSIS
#include <math.h>
double round(double x);
float roundf(float x);
long double roundl(long double x);
DESCRIPTION
These functions round x to the nearest integer, but round
halfway cases away from zero (regardless of the current
rounding direction), instead of to the nearest even inte
ger like rint().
RETURN VALUE
The rounded integer value. If x is integral or infinite, x
itself is returned.
ERRORS
No errors other than EDOM and ERANGE can occur. If x is
NaN, then NaN is returned and errno may be set to EDOM.
NOTES
The Austin draft contains text about overflow (which might
set errno to ERANGE, or raise an exception). In practice,
the result cannot overflow on any current machine, so this
error-handling stuff is just nonsense. (More precisely,
overflow can happen only when the maximum value of the
exponent is smaller than the number of mantissa bits. For
the IEEE-754 standard 32-bit and 64-bit floating point
numbers the maximum value of the exponent is 128 (resp.
1024), and the number of mantissa bits is 24 (resp. 53).)
CONFORMING TO
C99.
SEE ALSO
ceil(3), floor(3), lround(3), nearbyint(3), rint(3),
trunc(3)
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