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) |
arg
to an integer value in floating-point format, using the current rounding mode.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.arg | - | floating point value |
The nearest integer value to arg
, according to the current rounding mode, is returned.
This function is not subject to any of the errors specified in math_errhandling.
If the implementation supports IEEE floating-point arithmetic (IEC 60559),
FE_INEXACT
is never raised arg
is ±∞, it is returned, unmodified arg
is ±0, it is returned, unmodified arg
is NaN, NaN is returned 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
).
#include <stdio.h> #include <math.h> #include <fenv.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
(C99)(C99)(C99)(C99)(C99)(C99)(C99)(C99)(C99) | rounds to an integer using current rounding mode with exception if the result differs (function) |
(C99)(C99)(C99) | rounds to nearest integer, rounding away from zero in halfway cases (function) |
(C99)(C99) | gets or sets rounding direction (function) |
C++ documentation for nearbyint |
© cppreference.com
Licensed under the Creative Commons Attribution-ShareAlike Unported License v3.0.
http://en.cppreference.com/w/c/numeric/math/nearbyint