round - round a number to the nearest integer

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

Math library (`libm`

, `-lm`

)

`#include <math.h>`

```
double round(double x);
```

```
#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)):

This function rounds `x`

to the nearest integer.

This function returns, as a `double`

, `x`

rounded to the nearest integer. You may safely cast that value to a `long`

(or an `int`

if it fits).

These functions return the rounded integer value.

If `x`

is integral, +0, -0, NaN, or infinite, `x`

itself is returned.

`#include <math.h>`

#include <stdio.h>

int main(void)
{
printf("This is CS%i\n", (int) round(49.5));
}

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 |

Thread safety | MT-Safe |

C11, POSIX.1-2008.

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 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.