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Re: I want to convert a list of integers to their negative self
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Re: I want to convert a list of integers to their negative self


  • Subject: Re: I want to convert a list of integers to their negative self
  • From: Michelle Steiner <email@hidden>
  • Date: Wed, 28 Feb 2001 23:18:45 -0800

On 2/28/01 8:38 PM, email@hidden <email@hidden> wrote:

>> set a to {"1", "3", "7"}
>>
>> repeat with i in a
>> set a to rest of a & i div -1
>> end repeat
>
>This is a great one! I'm not sure I understand exactly how it does it, but
>thanks.

"Rest of" returns the all but the first element of a list (e.g., rest of
{"1", "3", "7"} returns {"3", "7"}.

"i div -1" returns -1. If i is a string representation of a number
(e.g., "1"), it is coerced to a number first.

So, set a to rest of a & "1" div -1 returns {"3", "7", -1}

Running it through the the loop uses the original list, and not the
modified list, for the iterations.

Logging each iteration

set a to {"1", "3", "7"}
log a
repeat with i in a
set a to rest of a & i div -1
log a
end repeat

(*1, 3, 7*)
(*3, 7, -1*)
(*7, -1, -3*)
(*-1, -3, -7*)

What is curious to me is that the log doesn't show the quotes around any
strings.

>One question though, only one person has even made reference to this
>and even that person didn't try this, but why not:
>
>set a to {1, 3, 7}
>
>in the first place. Does the original list have to be a list of strings or
>can you just make it a list of integers to begin with?

Yes, you can use integers to begin with, or even reals; I used strings in
my solution because that's how the problem was presented.

--Michelle

----------------------------------------------------------------------
| Michelle Steiner | We're not human beings having a spiritual |
| | experience. We're spiritual beings |
| email@hidden | having a human experience. |
----------------------------------------------------------------------


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