11 Jan
2017
11 Jan
'17
7:01 a.m.
On 11/01/2017 14:07, Noel Chiappa wrote:
Although I note the documentation says "any valid
value recognised by BBC
BASIC" - does BBC basic use the leading '%' notation for constants?
Sort of. BBC BASIC uses the prefix '&' to specify hexadecimal numbers,
so &FFFE is the exact equivalent of 0xFFFE in C. Similarly, BASIC IV
and later (IIRC) use '%' to represent binary, thus %11111110 is the
exact equivalent of 0xFE in C. Anything without a prefix is decimal.
The use of "%o" for an octal constant is specific to Jonathan's PDP-11
cross-assembler, though, and isn't part of BBC BASIC.
There are additional prefixes in BBC BASIC, but used for indirection
rather than base notations. There are also other uses for '%' as a
suffix, to denote special integer variables with single-character names
which have fixed size and location (eg A%, B%, and @% which is used for
print formatting).
--
Pete
Pete Turnbull