Re: Numeric Literals (Summary 4)

[Michael Lazzaro]

On Friday, November 22, 2002, at 03:31  AM, Anton Berezin wrote:

This:

- radix > 36, only colon form is allowed, not alpha digits

implies that this:

  256#0_253_254_255   # base 256, NOT identical!

is actually not allowed, no?

Ick, good point. In theory, the second of those was supposed to mean:

256#0253254255

but while all of those are valid digits in radix 256, the # syntax doesn't _allow_ digits in radix > 36, only integer representations of digits.

So I believe you are correct. The second should give a syntax error, because 256# is looking for colon-separated integers, _not_ alphanumeric digits, and the value 0253254255 is > 255 (the max digit size of base 256).

So we have:

16#00ff # OK, == 0xff
16#00_ff # OK, == 0xff
16#5 # OK, == 0x05
16#f # OK, == 0x0f
16#15 # OK, == 0x15
16#0:15 # OK, == 0x0f
16#0:0:15:15 # OK, == 0x00ff
16#0:0:f:f # WRONG, colon style uses only decimal integers

256#05 # OK, == 256#0:05
256#0_5 # WRONG, 05 is one "digit", not two
256#f # WRONG, (would be 256#0:f)
256#1234 # WRONG, 1234 > max digit (255)
256#12_34 # WRONG, 1234 > max digit (255)
256#0:253:254:255 # OK
256#0:fd:fe:ff # WRONG
256#0:0xfd:0xfe:0xff # WRONG

I'll revise.

MikeL