ftp.cs.arizona.edu/ftp.cs.arizona.edu.tar/ftp.cs.arizona.edu/icon/newsgrp/group97a.txt/000011_icon-group-sender _Mon Jan 6 11:23:17 1997.msg

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Date: Mon, 6 Jan 1997 11:23:17 -0800
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To: [e-mail], Icon Group <[e-mail]>
From: Bob Alexander <[e-mail]>
Subject: Re: Another Question from the Neophyte
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>But I've run into a new problem.  I have found numerous options for
>scanning forward in a string, but I haven't found a good way to move
>backwards, besides first reversing a string and then scanning forward
>(which is functionally scanning backwards).

Here's a way to solve your problem without reverse scanning:

procedure main()
  while line := read() do line ? {
    every i := 0 | upto(' ')
    write(line[i + 1:0])
  }
end

Scanning in Icon is most definitely biased toward left-to-right scanning,
however the cursor (&pos) can be moved "backward" for certain problems.
E.g. the argument to move() can be negative, and tab() can take you toward
the left, too.  You can also write your own scanning functions to move the
cursor backward.  This might invoke the wrath of some scanning purists, but
it works for some things.

However, as shown above, sometimes there is a completely different way of
approaching a problem that appears to involve backward scanning.

-- Bob Alexander
   [e-mail]