Originální popis anglicky:
round, roundf, roundl - round to nearest integer, away from zero
Návod, kniha: Linux Programmer's Manual
#include <math.h>
double round(double x);
float roundf(float x);
long double roundl(long double x);
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().
The rounded integer value. If
x is integral or infinite,
x itself
is returned.
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 1003.1-2001 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).)
C99.
ceil(3),
floor(3),
lround(3),
nearbyint(3),
rint(3),
trunc(3)
