Re^4: $a++ allowed by $a-- is not ! why?

As long as you can mix numbers with letters the problem remains.

no, the signature does not allow to mix letters with numbers. if we allowed this, that means:

++: /\A[a-z0-9]*\z/ -> /\A[a-z0-9]*\z/
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, what is the difference between this addition and the addition in a 36-ary number system? (have fun with this link)
the only problem here is that the first character must not be a number, thus the awkward domains:

kabel@linux:~> perl
my $num = "1hiho";
print ++ $num, $/;
2
kabel@linux:~>
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What about "-1"?

"-1" is an illegal input. harhar. ;-)

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Re: Re^4: $a++ allowed by $a-- is not ! why? by demerphq (Chancellor) on Sep 01, 2003 at 11:02 UTC
the signature does not allow to mix letters with numbers. I think we are at cross purposes here. It does allow them to be mixed, you may have any set of letters followed by any set of numbers and ++ will "work". This means that you still have the problem we have been discussing as there is no mapping from 9 to 'a0' but there is a mapping from 'a0' to 9. --- demerphq _{<Elian> And I do take a kind of perverse pleasure in having an OO assembly language...}	[reply] [d/l]

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Re: Re^4: $a++ allowed by $a-- is not ! why?
by demerphq (Chancellor) on Sep 01, 2003 at 11:02 UTC

the signature does not allow to mix letters with numbers.

I think we are at cross purposes here. It does allow them to be mixed, you may have any set of letters followed by any set of numbers and ++ will "work". This means that you still have the problem we have been discussing as there is no mapping from 9 to 'a0' but there is a mapping from 'a0' to 9.

_{<Elian> And I do take a kind of perverse pleasure in having an OO assembly language...}

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