округлить до ближайшего целого числа (round to nearest integer)
Имя (Name)
nearbyint, nearbyintf, nearbyintl, rint, rintf, rintl - round to
nearest integer
Синопсис (Synopsis)
#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);
Link with -lm.
Feature Test Macro Requirements for glibc (see
feature_test_macros(7)):
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
Описание (Description)
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.
Возвращаемое значение (Return value)
These functions return the rounded integer value.
If x is integral, +0, -0, NaN, or infinite, x itself is returned.
Ошибки (Error)
No errors occur. POSIX.1-2001 documents a range error for
overflows, but see NOTES.
Атрибуты (Attributes)
For an explanation of the terms used in this section, see
attributes(7).
┌──────────────────────────────────────┬───────────────┬─────────┐
│Interface │ Attribute │ Value │
├──────────────────────────────────────┼───────────────┼─────────┤
│nearbyint(), nearbyintf(), │ Thread safety │ MT-Safe │
│nearbyintl(), rint(), rintf(), │ │ │
│rintl() │ │ │
└──────────────────────────────────────┴───────────────┴─────────┘
Стандарты (Conforming to)
C99, POSIX.1-2001, POSIX.1-2008.
Примечание (Note)
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 128 (respectively, 1024), and the number
of mantissa bits 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.
Смотри также (See also)
ceil(3), floor(3), lrint(3), round(3), trunc(3)
