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The problem is that the list ($a .. ++$a) is not evaluating a list like you think it is. It is not doing:
$start = $a; $end = ++$a; for ($_ = $start; $_ <= $end; $_++) { ... }
But rather, it is evaluating its endpoints, and then constructing the list from that. That is the cause of your problem:
for (++$x .. $x++ . $x) { ... } # starting at ++$x # ending at $x++ . $x # THE END HAS MODIFIED THE START
You can witness a similar result from:
print ++$x, ++$x, ++$x; # 333
You see, the arguments to a function aren't copies of the variables, but rather aliases -- by modifying ONE of the $x's, you've modified the others as well.

Knowing this, the output of this program makes sense to me:

$x = 3; print ++$x/$x--; # 3/4 => 0.75
Why is that? Well, the numerator is ++$x, and the denominator is $x--; but in subtracting 1 from $x in the denominator, we have now altered the numerator back to its original state!

I've worked out a solution to your 1 .. 12 loop, then.

for (++$x .. $x++ . $x--) { ... } # or for (++$....$.++.$.--) { ... }
See if you can work out why the starting point is 1.

japhy -- Perl and Regex Hacker

In reply to Re: Re: Re: For loop problem by japhy
in thread For loop problem by srawls

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