Objective-C中的`isNan` [英] `isNan` in Objective-C

问题描述

Objective-C有一个类似的函数isNan （Javascript示例）吗？我刚刚注意到这段代码导致显示 Nan％，所以我需要检测一个值是Nan，所以我可以将它改为0.。

There a function like isNan (Javascript example) for Objective-C? I just noticed this code is causing to display Nan %, so I need to detect is a value is Nan so I could change it to 0.

[portefeuillePercentWaarde setText:[NSString stringWithFormat:@"%.2f%%", verschilPrencentage]];

推荐答案

尝试添加

#include <math.h>

然后使用标准 isnan（）功能测试。

and then using the standard isnan() function to test.

你也可以使用NaN不等于任何东西的技巧，包括它自己：

You can also use the "trick" that NaN is not equal to anything, including itself:

double x;

// do some operation here
x = doSomething();
if (x != x)
  printf("%g is probably NaN, it's not equal to itself\n", x);

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