Re: seek question

I can't say I've ever run across an if() statement used as such, I assume that it's doing a if ($. == 1) from 1 to 3 implicitly, but I'm unsure.

One thing I do know is that seek does not reset the line number variable $. when positioning back to the beginning of the file, so you have to set it explicitly:

use warnings;
use strict;

my $f = "/etc/fstab";
open ( my $fh, "<", $f );

while ( <$fh> ) {
    print "$.: $_";
}

print "=" x 78, "\n\n";
print "after 1st while loop\n";

seek( $fh, 0, 0);

# reset line num

$. = 0;

while ( <$fh> ) {
    print if (1..3);
}
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Re^2: seek question by kcott (Archbishop) on Feb 10, 2017 at 06:42 UTC
G'day stevieb, OP wrote: "`... if (1..3) ...`" You wrote: "I can't say I've ever run across an `if()` statement used as such, I assume that it's doing a `if ($. == 1)` from 1 to 3 implicitly, but I'm unsure." From "perlop: Range Operators": "If either operand of scalar `".."` is a constant expression, that operand is considered true if it is equal (`==`) to the current input line number (the `$.` variable)." — Ken	[reply] [d/l] [select]
Re^2: seek question by Marshall (Canon) on Feb 09, 2017 at 21:34 UTC
The seek() function deals with bytes. It knows nothing at all about "lines" or line numbers. Of course in this case, you could close the file and then re-open it to reset the $. line counter. I've never had to do that, but it would work.	[reply]
Re^3: seek question by stevieb (Canon) on Feb 09, 2017 at 21:42 UTC
I understand that, but OP was looping over the file handle which does use `$.`. I just meant that `seek()` does not reset this when going back to first row, first column, so that has to be done manually. I concur that closing/re-opening the handle would have the same effect as `$. = 0;`.	[reply] [d/l] [select]