c# - Can you compare floating point values exactly to zero?

Question

I know we can't compare 2 floating point values using ==. We can only compare they are within some interval of each other. I know

if(val == 0.512)

is wrong due to errors inherent in floating point calculations and conversion to binary and should be

if (val in (0.512-epsilon, 0.512+epsilon))

But is 0 special? Can we compare floats exactly to 0? Or even that is incorrect? Particularly in the context of C# and Java?

double val = 0;
val = getVal();
if(val == 0)

Answer 1

Even though 0 has an exact representation, you can't rely on the result of a calculation using floats to be exactly 0. As you noted, this is due to floating point calculation and conversion issues.

So, you should test for 0 against your tolerance epsilon.