On Apr 13, 8:54 am, [email protected] (Shawn H Corey) wrote:
> C.DeRykus wrote:
> > Clear as mud? Did you say 'Hell, no'...? Go then and
> > meditate on autoincrement magic, grasshopper. When
> > enlightenment comes, please report back and explain it
> > to us too...
>
> Actually, it is because string-comparison operators order strings
> differently than auto-increment.
>
> String ordering by auto-increment:
> "a"
> "b"
> ...
> "y"
> "z"
> "aa"
> "ab"
> ...
> "yy"
> "yz"
> "za"
> "zb"
> ...
>
> String ordering by string-comparison operators:
> "a"
> "aa"
> "aaa"
> ...
> "y"
> "ya"
> "yaa"
> ...
> "yz"
> "yzz"
> "yzzz"
> ...
> "z"
> "za"
> "zaa"
> ...
>
> Notice that "z" appears in very different place in each.
>
Yes, you're right. But I mentioned "enlightenment" because
the auto-increment algorithm itself is somewhat mysterious.
And, here's the doozy for me as I tried remembering:
If the final value specified is not in the sequence that the
magical increment would produce, the sequence continues
until the next value is longer than the final value specified.
^^^^^^
So, in the OP's 'u'..'z' example, the expansion stops at 'yz'
because another increment would be 'za' which is 'longer'
than the final value specified'; whereas, 'yz' isn't:
'z' 122
'aa' 97 97
...
'yz' 121 122 ---> 'shorter' than 122
'za' 122 97 ----> 'longer' than 122
In other words, the sequencing continues until there's
carry past the final 'z'. I think that's the 'long and short
of it... maybe I've auto-enlightened myself..
--
Charles DeRykus
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