roundeven, roundevenf, roundevenl
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Defined in header
<math.h>
float roundevenf( float arg );
(1)
(since C23)
double roundeven( double arg );
(2)
(since C23)
long double roundevenl( long double arg );
(3)
(since C23)
Defined in header
<tgmath.h>
#define roundeven( arg )
(4)
(since C23)
1-3) Computes the nearest integer value to arg (in floating-point format), rounding halfway cases to nearest even integer, regardless of the current rounding mode.
4) Type-generic macro: If arg has type long double,
roundevenl is called. Otherwise, if arg has integer type or the type double, roundeven is called. Otherwise, roundevenf is called, respectively.[edit] Parameters
arg
-
floating-point value
[edit] Return value
If no errors occur, the nearest integer value to arg, rounding halfway cases to nearest even integer, 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):
- FE_INEXACT is never raised.
- If arg is ±∞, it is returned, unmodified.
- If arg is ±0, it is returned, unmodified.
- If arg is NaN, NaN is returned.
[edit] Example
Run this code
#include <math.h> #include <stdio.h> int main(void) { printf ("roundeven(+2.4) = %+.1f\n", roundeven(2.4)); printf ("roundeven(-2.4) = %+.1f\n", roundeven(-2.4)); printf ("roundeven(+2.5) = %+.1f\n", roundeven(2.5)); printf ("roundeven(-2.5) = %+.1f\n", roundeven(-2.5)); printf ("roundeven(+2.6) = %+.1f\n", roundeven(2.6)); printf ("roundeven(-2.6) = %+.1f\n", roundeven(-2.6)); printf ("roundeven(+3.5) = %+.1f\n", roundeven(3.5)); printf ("roundeven(-3.5) = %+.1f\n", roundeven(-3.5)); printf ("roundeven(-0.0) = %+.1f\n", roundeven(-0.0)); printf ("roundeven(-Inf) = %+f\n", roundeven(-INFINITY)); }
Possible output:
roundeven(+2.4) = +2.0 roundeven(-2.4) = -2.0 roundeven(+2.5) = +2.0 roundeven(-2.5) = -2.0 roundeven(+2.6) = +3.0 roundeven(-2.6) = -3.0 roundeven(+3.5) = +4.0 roundeven(-3.5) = -4.0 roundeven(-0.0) = -0.0 roundeven(-Inf) = -inf
[edit] References
- C23 standard (ISO/IEC 9899:2024):
- 7.12.9.8 The roundeven functions (p: 265-266)
- 7.27 Type-generic math <tgmath.h> (p: 386-390)
- F.10.6.8 The roundeven functions (p: 532)
[edit] See also
(C99)(C99)(C99)(C99)(C99)(C99)(C99)(C99)(C99)
exception if the result differs
(function) [edit]
(C99)(C99)(C99)(C99)(C99)(C99)(C99)(C99)(C99)
(function) [edit]