如何在Objective-C(iOS)中检查NaN值 [英] How to check for NaN value in Objective-C (iOS)

问题描述

可能的重复项:
Objective-C-浮动检查nan
确定NSNumber是否为NaN

Possible Duplicates:
Objective-C - float checking for nan
Determine if NSNumber is NaN

我在CGFloat中的NaN值有问题，如何检查该数字是否有效?

I have a problem with NaN values in CGFloat, how can I check if the number is valid?

到目前为止唯一可行的方法是:

the only way so far that works is:

if ([[NSString stringWithFormat:@"%f", output] isEqualToString:@"nan"]) {
    output = 0;
}

这根本不是一个很好的解决方案！ :) ...而且我很确定我还有其他事情要做.

which is not a nice solution at all! :) ... and I am pretty sure that there is something else I should do instead.

推荐答案

有一个定义，用于检查math.h中的数字是否为nan inf等(我认为您可以在不导入的情况下使用它).

There is a define for checking if a number is nan inf etc in math.h (you can use it without import I think).

isnan(myValue)

如果遵循定义，则最终会得到

if you follow the define you will end up with

(x!=x)

还有其他一些有用的定义，例如isinf， isnormal ，是有限的，...

there are also some other useful defines like isinf, isnormal , isfinite , ...

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