Is checking a double for equality ever safe?

Question

I have the following code:

double x = 0;

{ ...do stuff ...}

if(x == 0){

}

I was always taught that you shouldn\'t check floats for equal

Answer 1

if you set it yourself and wish to see if it ever changed you can safely check for equality (like using a sentinel value) though NaN is safer for things like that

float x=Float.NaN;
{
   //some code that may or may not set x
}
if(Float.isNaN(x))//it never got set