NAME

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

LIBRARY

       Math library (libm, -lm)

SYNOPSIS

       #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

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 were added in glibc 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 │
       └───────────────────────────────────────────────────────────────┴───────────────┴─────────┘

STANDARDS

       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 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 lround(3) instead.

SEE ALSO

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