问题
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.
回答1:
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 , ...
来源：https://stackoverflow.com/questions/6220798/how-to-check-for-nan-value-in-objective-c-ios