How to check for NaN value in Objective-C (iOS)

Question

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?

the only way so far that works is:

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.

A chain of dupes, even: [Objective C - float checking for nan](http://stackoverflow.com/questions/3471988/objective-c-float-checking-for-nan) to [isNan in objective c](http://stackoverflow.com/questions/2109257/isnan-in-objective-c) to [Determine if NSNumber is NaN](http://stackoverflow.com/questions/719417/determine-if-nsnumber-is-nan) — jscs, Jun 03 '11 at 00:26
I believe [this question](http://stackoverflow.com/questions/3471988/objective-c-float-checking-for-nan) has the answer to your problem. — makdad, Jun 02 '11 at 21:52

thomas · Accepted Answer · 2011-06-02T22:04:55.463

153

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)

if you follow the define you will end up with

(x!=x)

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

edited Jun 02 '11 at 22:04

answered Jun 02 '11 at 21:58

thomas

1 Answers1