如何在C ++中检查浮点数是正无穷大？ [英] How to check in C++ that a floating point number is just positive infinity?

问题描述

我知道< cmath> isinf（c ++ 11）或更早版本< float.h> _finite函数/宏测试给定的浮点数是否为
EITHER 正无穷大 OR 负无穷大但我想知道某个数字是否只是正无穷大I.E.与isinf或_finite不同，IsPositiveInfinity（-1.0 / 0.0）返回
false 同样我想知道是否有办法测试浮点数是否只是负无穷大I.E. IsNegativeInfinity（numeric_limits< double> :: infinity（））也返回false，因为numeric_limits< double> :: infinity（）
返回double类型的正无穷大值！

I我不想发布这个，但我在整个互联网上找不到这个问题的答案，所以我别无选择！太奇怪了！

解决方案

也许你应该把 isinf 与"> 0"结合起来：

    bool is_positive_infinity = isinf（number）&&数字> 0;

I know that the <cmath> isinf (c++11) or older <float.h> _finite functions/macros test whether the given floating point number is EITHER positive infinity OR negative infinity But I want to know if some number is just positive infinity I.E. IsPositiveInfinity(-1.0 / 0.0) returns false unlike isinf or _finite Also I want to know if there is a way to test whether a floating point number is just negative infinity I.E. IsNegativeInfinity(numeric_limits<double>::infinity()) also returns false, because numeric_limits<double>::infinity() returns positive infinity value of type double!

I didn't want to post this, but I couldn't find answer to this question in the whole internet, so I don't have no choice! So weird!

解决方案

Perhaps you should combine isinf with ">0":

    bool is_positive_infinity = isinf( number ) && number > 0;

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