# rint(3) — Linux manual page

```rint(3)                 Library Functions Manual                 rint(3)
```

## NAME         top

```       nearbyint, nearbyintf, nearbyintl, rint, rintf, rintl - round to
nearest integer
```

## LIBRARY         top

```       Math library (libm, -lm)
```

## SYNOPSIS         top

```       #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

rintf(), rintl():
_ISOC99_SOURCE || _POSIX_C_SOURCE >= 200112L
|| /* Since glibc 2.19: */ _DEFAULT_SOURCE
|| /* glibc <= 2.19: */ _BSD_SOURCE || _SVID_SOURCE
```

## DESCRIPTION         top

```       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.
```

## RETURN VALUE         top

```       These functions return the rounded integer value.

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

## ERRORS         top

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

## ATTRIBUTES         top

```       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()                             │               │         │
└─────────────────────────────────────┴───────────────┴─────────┘
```

## STANDARDS         top

```       C11, POSIX.1-2008.
```

## HISTORY         top

```       C99, POSIX.1-2001.
```

## NOTES         top

```       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)
```       ceil(3), floor(3), lrint(3), round(3), trunc(3)