nearbyint, nearbyintf, nearbyintl, rint, rintf, rintl - round to nearest integer
Math library (
libm,
-lm)
#include <math.h>
double nearbyint(double x);
float nearbyintf(float x);
long double nearbyintl(long double x);
double rint(double x);
float rintf(float x);
long double rintl(long double x);
nearbyint(),
nearbyintf(),
nearbyintl():
_POSIX_C_SOURCE >= 200112L || _ISOC99_SOURCE
rint():
_ISOC99_SOURCE || _POSIX_C_SOURCE >= 200112L
|| _XOPEN_SOURCE >= 500
|| /* Since glibc 2.19: */ _DEFAULT_SOURCE
|| /* glibc <= 2.19: */ _BSD_SOURCE || _SVID_SOURCE
rintf(),
rintl():
_ISOC99_SOURCE || _POSIX_C_SOURCE >= 200112L
|| /* Since glibc 2.19: */ _DEFAULT_SOURCE
|| /* glibc <= 2.19: */ _BSD_SOURCE || _SVID_SOURCE
The
nearbyint(),
nearbyintf(), and
nearbyintl() functions
round their argument to an integer value in floating-point format, using the
current rounding direction (see
fesetround(3)) and without raising the
inexact exception. When the current rounding direction is to nearest,
these functions round halfway cases to the even integer in accordance with
IEEE-754.
The
rint(),
rintf(), and
rintl() functions do the same, but
will raise the
inexact exception (
FE_INEXACT, checkable via
fetestexcept(3)) when the result differs in value from the argument.
These functions return the rounded integer value.
If
x is integral, +0, -0, NaN, or infinite,
x itself is returned.
No errors occur. POSIX.1-2001 documents a range error for overflows, but see
NOTES.
For an explanation of the terms used in this section, see
attributes(7).
Interface |
Attribute |
Value |
nearbyint (), nearbyintf (), nearbyintl (), rint (), rintf (), rintl
() |
Thread safety |
MT-Safe |
C99, POSIX.1-2001, POSIX.1-2008.
SUSv2 and POSIX.1-2001 contain text about overflow (which might set
errno
to
ERANGE, or raise an
FE_OVERFLOW 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 127 (respectively, 1023), and the number of mantissa bits
including the implicit bit is 24 (respectively, 53).)
If you want to store the rounded value in an integer type, you probably want to
use one of the functions described in
lrint(3) instead.
ceil(3),
floor(3),
lrint(3),
round(3),
trunc(3)