round, roundf, roundl — round to nearest integer, away from zero
#include <math.h>
double round( |
double | x) ; |
float
roundf( |
float | x) ; |
long
double roundl( |
long double | x) ; |
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Note |
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Compile with −std=c99; link with −lm. |
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 integer
like rint(3).
No errors other than EDOM and ERANGE can occur. If
x
is NaN, then NaN is
returned and errno
may be set to
EDOM.
POSIX.1-2001 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).)
ceil(3), floor(3), lround(3), nearbyint(3), rint(3), trunc(3)
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