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);
```

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
```

```
_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 |

C11, POSIX.1-2008.

C99, POSIX.1-2001.

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.