This works as a quirk of the flip/flop operator. From the documentation "If either operand of scalar ``..'' is a constant expression, that operand is implicitly compared to the $. variable, the current line number." The statement scalar tell(STDIN) must set $. = 0 (although I don't know why) changing the line from scalar tell(STDIN); to $. = 0; gives the same result. 

use strict;
use warnings;

my $firsttime = 1;

my $line1 = <DATA>;
print neverflop();
$firsttime = 0;

my $line2 = <DATA>;
print neverflop();

#scalar tell(STDIN);
$. = 0;
print neverflop();
print neverflop();

sub neverflop {
   my $statecount = ($firsttime .. 0);
   ($firsttime .. 0) ? "flip$statecount\t" : "flop$statecount\t";
}

__DATA__
line1
line2
line3

__END__
flip1   flip2   flip3E0 flop

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PJ
use strict; use warnings; use diagnostics; (if needed)

In reply to Re^3: blank lines up to a point by periapt
in thread blank lines up to a point by Anonymous Monk

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