ROUND
NAME SYNOPSIS DESCRIPTION RETURN VALUE ERRORS NOTES CONFORMING TO SEE ALSO
round, roundf, roundl - round to nearest integer, away from zero
#include x); float roundf(float x); long double roundl(long double x);
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.
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).)
C99.
ceil(3), floor(3), lround(3), nearbyint(3), rint(3), trunc(3)
