Question

So I (think I) understand the difference between Float, Double, and Decimal, but one thing that I’ve wondered about is why there are two sizes of floating binary point, but only one size of floating decimal point?

If I understand the general principle correctly, you’d want to use a float(32-bit) for performance over a double (64-bit) on a 32-bit processor, if you don’t need the extra size of the double. On a 64-bit processor, the double should be more performant so this rationale isn’t as necessary. But the Decimal type is 128-bits. So why not offer a 64-bit decimal, or even a 32-bit?

Is it just a matter of use cases; no one really needed it? Or is there a technical reason, like you can’t accurately present useful decimal ranges with less than 128 bits?

Answer 1

Mandatory link to Eric Lippert’s Features start off as unimplemented and only become implemented when people spend effort implementing them.

Why it would not be good idea:

• any additional numeric type requires a lot of conversions from / to other numeric types, along with rules for which ones are allowed and which ones are not.
• smaller types (especially 32 bit) would simply not have useful range – i.e. reasonable price range of an item is at least 8 digits 12345.67(0 tenth of lowest money unit).