Re^3: blank lines up to a point

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
[download]

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

Comment on Re^3: blank lines up to a point Download Code

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Re^4: blank lines up to a point by ysth (Canon) on Sep 15, 2004 at 15:00 UTC
$. is stored per-filehandle, and automatically refers to the last input file. Any of readline, tell, seek, sysseek, or eof will change the last input file. You could just use: `/\S/ .. my $false` [download] instead.	[reply] [d/l]
Re^5: blank lines up to a point by SpanishInquisition (Pilgrim) on Sep 15, 2004 at 19:04 UTC
Can any operator that inspires this much confusion be a GoodThing (TM)? Don't answer that. It's a rhetorical question.	[reply]