roundeven, roundevenf, roundevenl
From cppreference.com
Common mathematical functions
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Defined in header <math.h>
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float roundevenf( float arg ); |
(1) | (since C23) |
double roundeven( double arg ); |
(2) | (since C23) |
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long
double roundevenl(
long
double arg )
;
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(3) | (since C23) |
Defined in header <tgmath.h>
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#define roundeven( arg ) |
(4) | (since C23) |
1-3) Computes the nearest integer value to arg
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
Parameters
| arg | - | floating-point value |
Return value
If no errors occur, the nearest integer value to arg, rounding halfway cases to nearest even integer, is returned.
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.
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
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)
See also
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(C99)
(C99)
(C99)
(C99)
(C99)
(C99)
(C99)
(C99)
(C99)
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rounds to an integer using current rounding mode with exception if the result differs (function) |
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(C99)
(C99)
(C99)
(C99)
(C99)
(C99)
(C99)
(C99)
(C99)
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rounds to nearest integer, rounding away from zero in halfway cases (function) |