David Blaikie wrote:
>
> What sort of string-like behavior would one want on a bit-string? Seems
> like array would be the better fit to me...
>
It's a language that originates in the late 60s - so there are some,
"different" ideas than more contemporary languages.
You can ask for sub-strings of strings (character or bit), you can
assign a string (shorter or of equal length) to a target string,
you can also concatenate strings, and you can assign to portions
within a target bit string (or character string for that matter.)
e.g.
test: proc;
dcl b10 bit(10);
dcl b20 bit(20) varying;
dcl dest bit(30) varying4; /* maximum possible result size */
b10 = '1010'b; /* assigns '1010000000' to b10 (passing on the right */
/* with 0 bits because the length is fixed. */
b20 = '10'b; /* assigns '10' to b20, moving a byte containing */
/* '10......' and setting the 2-byte length field */
/* to 2, indicating the left-most 2 bits are used. */
dest = b10 || b20; /* assigns '101000000010....' to dest, setting it's */
/* 4-byte length field to 12. */
b10 = substr(dest,1,2); /* extracts the first 2 bits from the bitfield */
/* dest ('10') (2 bytes starting a position #1) and assigns */
/* it to b10, which is extended to 10 bits on-the-right */
/* because b10 is a fixed-length, resulting in '1000000000' */
/* being assigned to b10 */
substr(b10,6,1) = '1'b; /* assigns a 1-bit value to b10, starting */
/* at bit #6 and going for 1 bit, resulting */
/* in '1010010000' being in b10 */
end proc;
So - it's a rather abstract idea of "strings of bits" similar to
"strings of characters".
- Dave Rivers -
--
riv...@dignus.com
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