Interesting behaviour of type “decimal” in C#

Question

If we declare padding as const decimal, the padding is not working.

mymoney = 1.2 and your money = 1.20, how can this behavior be explained?

class Progra         


        

Answer 1

The compiler "knows" that adding zero to a value "shouldn't" change the value - so it optimizes this out. Now arguably that's an invalid optimization given the nature of decimal addition, but if you look at the generated code, you'll find the computation of mymoney doesn't involve an addition.

I don't think I'd try to use adding 0.00m as a way to ensure a particular scale, to be honest. You could create your own code to enforce the scale, using decimal.GetBits and the constructor performing the reverse operation - but I don't think it would be terribly nice.

Do you definitely need this "two decimal places" form as an intermediate value, or is it only for presentation? If it's the latter, I'd look at format strings instead.