round(3) — Справочная страница Linux

round(3)                Library Functions Manual                round(3)

ИМЯ

       round, roundf, roundl - round to nearest integer, away from zero

БИБЛИОТЕКА

       Math library (libm, -lm)

СИНТАКСИС

       #include <math.h>

       double round(double x);
       float roundf(float x);
       long double roundl(long double x);

   Feature Test Macro Requirements for glibc (see
   feature_test_macros(7)):

       round(), roundf(), roundl():
           _ISOC99_SOURCE || _POSIX_C_SOURCE >= 200112L

ОПИСАНИЕ

       These functions round x to the nearest integer, but round halfway
       cases away from zero (regardless of the current rounding
       direction, see fenv(3)), instead of to the nearest even integer
       like rint(3).

       For example, round(0.5) is 1.0, and round(-0.5) is -1.0.

ЗНАЧЕНИЕ, ВОЗВРАЩАЕМОЕ ФУНКЦИЕЙ

       These functions return the rounded integer value.

       If x is integral, +0, -0, NaN, or infinite, x itself is returned.

ОШИБКИ

       No errors occur.

АТРИБУТЫ

       For an explanation of the terms used in this section, see
       attributes(7).
       ┌─────────────────────────────────────┬───────────────┬─────────┐
       │ Interface                           │ Attribute     │ Value   │
       ├─────────────────────────────────────┼───────────────┼─────────┤
       │ round(), roundf(), roundl()         │ Thread safety │ MT-Safe │
       └─────────────────────────────────────┴───────────────┴─────────┘

СТАНДАРТЫ

       C11, POSIX.1-2008.

ИСТОРИЯ

       glibc 2.1.  C99, POSIX.1-2001.

       POSIX.1-2001 contains 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 was 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).)  This
       was removed in POSIX.1-2008.

       If you want to store the rounded value in an integer type, you
       probably want to use one of the functions described in lround(3)
       instead.

СМОТРИТЕ ТАКЖЕ

       ceil(3), floor(3), lround(3), nearbyint(3), rint(3), trunc(3)

КОЛОФОН

       This page is part of the man-pages (Linux kernel and C library
       user-space interface documentation) project.  Information about
       the project can be found at 
       ⟨https://www.kernel.org/doc/man-pages/⟩.  If you have a bug report
       for this manual page, see
       ⟨https://git.kernel.org/pub/scm/docs/man-pages/man-pages.git/tree/CONTRIBUTING⟩.
       This page was obtained from the tarball man-pages-6.9.1.tar.gz
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       2024-06-26.  If you discover any rendering problems in this HTML
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       man-pages@man7.org

Linux man-pages 6.9.1          2024-06-16                       round(3)

Страницы, ссылающиеся на эту страницу: ceil(3), floor(3), lrint(3), lround(3), rint(3), roundup(3), trunc(3)