Question

I’m designing a language, and trying to decide whether true should be 0x01 or 0xFF. Obviously, all non-zero values will be converted to true, but I’m trying to decide on the exact internal representation.

What are the pros and cons for each choice?

Answer 1

0 is false because the processor has a flag that is set when a register is set to zero.

No other flags are set on any other value (0x01, 0xff, etc) – but the zero flag is set to false when there’s a non-zero value in the register.

So the answers here advocating defining 0 as false and anything else as true are correct.

If you want to "define" a default value for true, then 0x01 is better than most:

• It represents the same number in every bit length and signedness
• It only requires testing one bit if you want to know whether it’s true, should the zero flag be unavailable, or costly to use
• No need to worry about sign extension during conversion to other types
• Logical and arithmetic expressions act the same on it