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std::signbit

STD：：Sibit

Defined in header ​​
bool signbit( float arg (1)(since C++11)
bool signbit( double arg (2)(since C++11)
bool signbit( long double arg (3)(since C++11)
bool signbit( Integral arg (4)(since C++11)

1-3%29确定给定的浮点数arg是阴性的。

4%29一组重载或接受from任何论点积分型等效于%282%29%28的参数转换为double29%。

参数

arg-floating point value

返回值

true如果arg是阴性的，false否则。

注记

此函数检测零、无穷大和nans的符号位。同std::copysignSignbit是检查NaN符号的两种可移植的方法之一。

实例

二次

#include <iostream>
#include <cmath>
 
int main()
{
    std::cout << std::boolalpha
              << "signbit(+0.0) = " << std::signbit(+0.0) << '\n'
              << "signbit(-0.0) = " << std::signbit(-0.0) << '\n';
}

二次

产出：

二次

signbit(+0.0) = false
signbit(-0.0) = true

二次

另见

abs(float) fabsabsolute value of a floating point value (|x|) (function)
copysign (C++11)copies the sign of a floating point value (function)

c Sibit文件

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