如何在 Objective-C (iOS) 中检查 NaN 值
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How to check for NaN value in Objective-C (iOS)
提问by Ondrej Rafaj
Possible Duplicates:
Objective-C - float checking for nan
Determine if NSNumber is NaN
I have a problem with NaN values in CGFloat, how can I check if the number is valid?
我对 CGFloat 中的 NaN 值有问题，如何检查数字是否有效？
the only way so far that works is:
到目前为止唯一有效的方法是：
if ([[NSString stringWithFormat:@"%f", output] isEqualToString:@"nan"]) {
output = 0;
}
which is not a nice solution at all! :) ... and I am pretty sure that there is something else I should do instead.
这根本不是一个好的解决方案！:) ...而且我很确定我应该做其他事情。
回答by thomas
There is a define for checking if a number is nan inf etc in math.h (you can use it without import I think).
在 math.h 中有一个用于检查数字是否为 nan inf 等的定义（我认为您可以在不导入的情况下使用它）。
isnan(myValue)
if you follow the define you will end up with
如果你遵循定义，你最终会得到
(x!=x)
there are also some other useful defines like isinf, isnormal, isfinite, ...
