nearbyint, nearbyintf, nearbyintl

Rounds the specified floating-point value to an integer, and returns that value in a floating-point format.

Syntax

double nearbyint( double x );
float nearbyintf( float x );
long double nearbyintl( long double x );
#define nearbyint( X ) // Requires C11 or higher

float nearbyint( float x ); //C++ only
long double nearbyint( long double x ); //C++ only

Parameters

x
The value to round.

Return value

If successful, returns x, rounded to the nearest integer, using the current rounding format as reported by fegetround. Otherwise, the function may return one of the following values:

Issue	Return
x = ±INFINITY	±INFINITY, unmodified
x = ±0	±0, unmodified
x = NaN	NaN

Errors aren't reported through _matherr; specifically, this function doesn't report any FE_INEXACT exceptions.

Remarks

The primary difference between this function and rint is that this function doesn't raise the inexact floating point exception.

Because the maximum floating-point values are exact integers, this function will never overflow by itself; rather, the output may overflow the return value, depending on which version of the function you use.

C++ allows overloading, so you can call overloads of nearbyint that take and return float or long double parameters. In a C program, unless you're using the <tgmath.h> macro to call this function, nearbyint always takes two double values and returns a double value.

If you use the <tgmath.h> nearbyint() macro, the type of the argument determines which version of the function is selected. See Type-generic math for details.

By default, this function's global state is scoped to the application. To change this behavior, see Global state in the CRT.

Requirements

Function	C header	C++ header
nearbyint, nearbyintf, nearbyintl	<math.h>	<cmath> or <math.h>
nearbyint macro	<tgmath.h>

For more compatibility information, see Compatibility.

See also

Alphabetical function reference
Math and floating-point support