When is a float variable not equal to itself

问题

I was asked this questino on a programming test. The question was, I was passed in a float as a parameter, and asked when would the following code be false.

bool result  = (floatValue == floatValue);

I couldn't think of a valid reason or a situation of when this would be false and still can't. In the end, I answered that there will never be a case when this would be false. Was wondering if anyone can give me some example(s) of when this would be false

回答1:

floatValue == NaN

If floatValue is the result of a computation that is Not a Number, like 0/0.

来源：https://stackoverflow.com/questions/32900284/when-is-a-float-variable-not-equal-to-itself