Does a foreach create a scalar reference?

hesco has asked for the wisdom of the Perl Monks concerning the following question:

This works, I just don't understand why. Can anyone please shed some light on why my timestamp elements are affected by my assignment to a locally scoped variable in a while loop? Does this foreach construct make $element a reference to the underlying list element?

-- Hugh

#!/usr/bin/perl -w
use strict;
use warnings;

my ($s,$m,$h,$dy,$mo,$yr,$t1,$t2,$t3) = localtime;

$mo++;
$yr += 1900;

foreach my $element ($s,$m,$h,$dy,$mo){
  $element = '0' . $element if(length($element) < 2);
  print $element, "\n";
}

print <<EndOfString;
$yr-$mo-$dy $h:$m
EndOfString
[download]

This produced output looking like this:

49
54
14
26
05
2009-05-26 14:54
[download]

if( $lal && $lol ) { $life++; }

Comment on Does a foreach create a scalar reference? Select or Download Code

Replies are listed 'Best First'.
Re: Does a foreach create a scalar reference? by DStaal (Chaplain) on May 26, 2009 at 19:19 UTC
From Perlsyn In other words, the foreach loop index variable is an implicit alias for each item in the list that you're looping over. In other words: Yes. It creates a reference. On a side note: I'm glad to see `use strict;` and `use warnings`, but you don't need `#!/usr/bin/perl -w` as well: The `-w` is basically a slightly dumbed-down version of `use warnings`, and is redundant in this code. (And unless you understand why I said 'in this code', is likely to cause you headaches someplace down the line if you keep using it.)	[reply] [d/l] [select]
Re: Does a foreach create a scalar reference? by jwkrahn (Abbot) on May 26, 2009 at 19:29 UTC
This behaviour is described in the third paragraph of the Foreach Loops section of the perlsyn document. But perhaps it would be simpler to use sprintf to add leading zeros to your numeric fields: `my ( undef, $m, $h, $dy, $mo, $yr ) = localtime; print sprintf "%d-%02d-%02d %02d:%02d\n", $yr + 1900, $mo + 1, $dy, $h +, $m;` [download]	[reply] [d/l]
Re^2: Does a foreach create a scalar reference? by Fletch (Bishop) on May 26, 2009 at 19:38 UTC
Or even cleaner just let strftime do the grunt work for you. The cake is a lie. The cake is a lie. The cake is a lie.	[reply]
Re: Does a foreach create a scalar reference? by shmem (Chancellor) on May 26, 2009 at 19:57 UTC
Does this foreach construct make $element a reference to the underlying list element? Yes, it does.	[reply]


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