std::nearbyint
STD：：近字节
| Defined in header | | |
|---|---|---|
| float nearbyint( float arg | (1) | (since C++11) |
| double nearbyint( double arg | (2) | (since C++11) |
| long double nearbyint( long double arg | (3) | (since C++11) |
| double nearbyint( Integral arg | (4) | (since C++11) |
1-3%29圈浮点参数arg以浮点格式设置的整数值，则使用电流舍入模式...
4%29一组过载或接受任意参数的函数模板积分型等效于%282%29%28的参数转换为double29%。
参数
| arg | - | floating point value |
|---|
返回值
最近的整数值arg，根据电流舍入模式，被归还。
错误处理
中指定的任何错误都不受此函数的影响。数学[医]错误处理...
如果实现支持ieee浮点算法%28IEC 60559%29，
FE_INEXACT永远不会被提起
- 如果
arg是±∞，它被返回，未经修改
- 如果
arg是±0，它被返回，未经修改
- 如果
arg是南，南回来了
注记
唯一的区别是std::nearbyint和std::rint那是std::nearbyint不养FE_INEXACT...
最大的可表示浮点值是所有标准浮点格式的精确整数，因此std::nearbyint永远不要自己溢出，但是结果可能会溢出任何整数类型%28，包括std::intmax_t%29，存储在整数变量中。
如果当前舍入模式是FE_TONEAREST，此函数在一半情况下会转到%28类似的情况。rint，但不像round29%。
例
二次
#include <iostream>
#include <cmath>
#include <cfenv>
int main()
{
#pragma STDC FENV_ACCESS ON
std::fesetround(FE_TONEAREST
std::cout << "rounding to nearest: \n"
<< "nearbyint(+2.3) = " << std::nearbyint(2.3)
<< " nearbyint(+2.5) = " << std::nearbyint(2.5)
<< " nearbyint(+3.5) = " << std::nearbyint(3.5) << '\n'
<< "nearbyint(-2.3) = " << std::nearbyint(-2.3)
<< " nearbyint(-2.5) = " << std::nearbyint(-2.5)
<< " nearbyint(-3.5) = " << std::nearbyint(-3.5) << '\n';
std::fesetround(FE_DOWNWARD
std::cout << "rounding down:\n"
<< "nearbyint(+2.3) = " << std::nearbyint(2.3)
<< " nearbyint(+2.5) = " << std::nearbyint(2.5)
<< " nearbyint(+3.5) = " << std::nearbyint(3.5) << '\n'
<< "nearbyint(-2.3) = " << std::nearbyint(-2.3)
<< " nearbyint(-2.5) = " << std::nearbyint(-2.5)
<< " nearbyint(-3.5) = " << std::nearbyint(-3.5) << '\n';
std::cout << "nearbyint(-0.0) = " << std::nearbyint(-0.0) << '\n'
<< "nearbyint(-Inf) = " << std::nearbyint(-INFINITY) << '\n';
}
二次
产出：
二次
rounding to nearest:
nearbyint(+2.3) = 2 nearbyint(+2.5) = 2 nearbyint(+3.5) = 4
nearbyint(-2.3) = -2 nearbyint(-2.5) = -2 nearbyint(-3.5) = -4
rounding down:
nearbyint(+2.3) = 2 nearbyint(+2.5) = 2 nearbyint(+3.5) = 3
nearbyint(-2.3) = -3 nearbyint(-2.5) = -3 nearbyint(-3.5) = -4
nearbyint(-0.0) = -0
nearbyint(-Inf) = -inf
二次
另见
| rintlrintllrint (C++11)(C++11)(C++11) | nearest integer using current rounding mode with exception if the result differs (function) |
|---|---|
| roundlroundllround (C++11)(C++11)(C++11) | nearest integer, rounding away from zero in halfway cases (function) |
| fegetroundfesetround (C++11)(C++11) | gets or sets rounding direction (function) |
c近字节文件
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