Why is a cast required for byte subtraction in C#? [duplicate]

Answer 1

FWIW, java also promotes bytes to int.

Answer 2

Try to run this C# code: object o = (byte)(1); o = (int)o; What do you expect? Now try :)

I think this is right:

Eric Lippert says, "I don't think of bytes as "numbers"; I think of them as patterns of bits that could be interpreted as numbers, or characters, or colors or whatever. If you're going to be doing math on them and treating them as numbers, then it makes sense to move the result into a data type that is more commonly interpreted as a number."

Perhaps byte is closer to char than to int.

Answer 3

Because arithmetic on bytes returns integers by default so of the two possible assignments the narrower type of zero (byte) is promoted to int (that of oColor.r - percent). Thus the type of the operation is an int. The compiler will not, without a cast, allow you to assign a wider type to a narrower type, because it's a lossy operation. Hence you get the error, unless you explicitly say "I know I'm losing some data, it's fine" with the cast.