NAME

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

SYNOPSIS

       #include <math.h>

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

       Link with -lm.

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

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

DESCRIPTION

       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.

RETURN VALUE

       These functions return the rounded integer value.

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

ERRORS

       No errors occur.  POSIX.1-2001 documents a range error for overflows, but see NOTES.

VERSIONS

       These functions first appeared in glibc in version 2.1.

ATTRIBUTES

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

CONFORMING TO

       C99, POSIX.1-2001, POSIX.1-2008.

NOTES

       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
       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 lround(3) instead.

SEE ALSO

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

COLOPHON

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       information  about  reporting  bugs,  and  the  latest  version  of  this   page,   can   be   found   at
       https://www.kernel.org/doc/man-pages/.

                                                   2017-09-15                                           ROUND(3)