Re: Perl forgets variable every other pass in loop???

On Aug 27, 4:23 pm, David Filmer <use...@xxxxxxxxxxxxxxx> wrote:
Greetings!

Kindly consider this code which illustrates my question:

#!/usr/bin/perl
use strict;

my $column_ref = [
{ 'description' => { 'align' => 'left' } },
{ 'total' => { 'align' => 'right' } },
];
for (1..6) {
foreach my $format_ref( @{$column_ref} ) {
my( $column, $attr_ref ) = each %{ $format_ref };
print "'$column', '$attr_ref'\t";
}
print "\n";
}
__END__

What I would EXPECT to see from this program is something like this:

'description', 'HASH(0x8206710)' 'total', 'HASH(0x81fd314)'
'description', 'HASH(0x8206710)' 'total', 'HASH(0x81fd314)'
'description', 'HASH(0x8206710)' 'total', 'HASH(0x81fd314)'
'description', 'HASH(0x8206710)' 'total', 'HASH(0x81fd314)'
'description', 'HASH(0x8206710)' 'total', 'HASH(0x81fd314)'
'description', 'HASH(0x816dc28)' 'total', 'HASH(0x8192258)'

But, for some strange reason, Perl seems to "forget" the value of
$column_ref on every OTHER pass. What I ACTUALLY see is this:

'description', 'HASH(0x816dc28)' 'total', 'HASH(0x8192258)'
'', '' '', ''
'description', 'HASH(0x816dc28)' 'total', 'HASH(0x8192258)'
'', '' '', ''
'description', 'HASH(0x816dc28)' 'total', 'HASH(0x8192258)'
'', '' '', ''

Can anyone tell me what is happening to $column_ref???




You're missing the inner most loop. To obtain the output you
desired, you should have written:

for (1 .. 6) {
for my $format_ref (@$column_ref) {
while (my ($c, $a) = each %$format_ref)
{
print "'$c', '$a'\t";
}
}
print "\n";
}


See 'perldoc -f each' -- you're incrementally
going through an iterator and printing the contents
of the null array that's returned when the
iterator is exhausted (on every other line).

--
Hope this helps,
Steven
.

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