nearbyint, nearbyintf, nearbyintl - cppreference.com (original) (raw)

Defined in header <math.h>
float nearbyintf( float arg ); (1) (since C99)
double nearbyint( double arg ); (2) (since C99)
long double nearbyintl( long double arg ); (3) (since C99)
Defined in header <tgmath.h>
#define nearbyint( arg ) (4) (since C99)

1-3) Rounds the floating-point argument arg to an integer value in floating-point format, using the current rounding mode.

  1. Type-generic macro: If arg has type long double, nearbyintl is called. Otherwise, if arg has integer type or the type double, nearbyint is called. Otherwise, nearbyintf is called, respectively.

Contents

[edit] Parameters

arg - floating-point value

[edit] Return value

The nearest integer value to arg, according to the current rounding mode, is returned.

[edit] Error handling

This function is not subject to any of the errors specified in math_errhandling.

If the implementation supports IEEE floating-point arithmetic (IEC 60559),

[edit] Notes

The only difference between nearbyint and rint is that nearbyint never raises FE_INEXACT.

The largest representable floating-point values are exact integers in all standard floating-point formats, so nearbyint never overflows on its own; however the result may overflow any integer type (including intmax_t), when stored in an integer variable.

If the current rounding mode is FE_TONEAREST, this function rounds to even in halfway cases (like rint, but unlike round).

[edit] Example

#include <fenv.h> #include <math.h> #include <stdio.h>   int main(void) { // #pragma STDC FENV_ACCESS ON fesetround(FE_TONEAREST); printf("rounding to nearest:\nnearbyint(+2.3) = %+.1f ", nearbyint(2.3)); printf("nearbyint(+2.5) = %+.1f ", nearbyint(2.5)); printf("nearbyint(+3.5) = %+.1f\n", nearbyint(3.5)); printf("nearbyint(-2.3) = %+.1f ", nearbyint(-2.3)); printf("nearbyint(-2.5) = %+.1f ", nearbyint(-2.5)); printf("nearbyint(-3.5) = %+.1f\n", nearbyint(-3.5));   fesetround(FE_DOWNWARD); printf("rounding down: \nnearbyint(+2.3) = %+.1f ", nearbyint(2.3)); printf("nearbyint(+2.5) = %+.1f ", nearbyint(2.5)); printf("nearbyint(+3.5) = %+.1f\n", nearbyint(3.5)); printf("nearbyint(-2.3) = %+.1f ", nearbyint(-2.3)); printf("nearbyint(-2.5) = %+.1f ", nearbyint(-2.5)); printf("nearbyint(-3.5) = %+.1f\n", nearbyint(-3.5));   printf("nearbyint(-0.0) = %+.1f\n", nearbyint(-0.0)); printf("nearbyint(-Inf) = %+.1f\n", nearbyint(-INFINITY)); }

Output:

rounding to nearest: nearbyint(+2.3) = +2.0 nearbyint(+2.5) = +2.0 nearbyint(+3.5) = +4.0 nearbyint(-2.3) = -2.0 nearbyint(-2.5) = -2.0 nearbyint(-3.5) = -4.0 rounding down: nearbyint(+2.3) = +2.0 nearbyint(+2.5) = +2.0 nearbyint(+3.5) = +3.0 nearbyint(-2.3) = -3.0 nearbyint(-2.5) = -3.0 nearbyint(-3.5) = -4.0 nearbyint(-0.0) = -0.0 nearbyint(-Inf) = -inf

[edit] References

[edit] See also