Hello hghosh,

how would I use $line directly in the while condition? And what makes that better than declaring it as I did?

I think LanX is recommending something along these lines:

while (my $line = <IN>) {
    chomp $line;
    ...
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which is simpler and clearer.

Also, if I left $_ as it is in the second, strictured code block, it would refer to the same $_ as the first block of code, right?

Not sure which blocks you’re referring to; but, just to be clear, $_ refers to the “current” (i.e., the most closely related) syntactic construct that sets it. For example:

use strict;
use warnings;

for ('A' .. 'C')
{
    print "Outer: \$_ = $_\n";

    for (10 .. 12)
    {
        print "    Inner: \$_ = $_\n";
    }

    print "Outer: \$_ = $_\n";
}
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produces:

23:21 >perl 2004_SoPW.pl
Outer: $_ = A
    Inner: $_ = 10
    Inner: $_ = 11
    Inner: $_ = 12
Outer: $_ = A
Outer: $_ = B
    Inner: $_ = 10
    Inner: $_ = 11
    Inner: $_ = 12
Outer: $_ = B
Outer: $_ = C
    Inner: $_ = 10
    Inner: $_ = 11
    Inner: $_ = 12
Outer: $_ = C

23:22 >
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— showing that there are actually as many independent instances of $_ (two, in this case) as the scoping requires.

Hope that helps,