Looping through an Array

[jarrodb]

Hello perl monks, I am trying to loop through an array but am stuck pulling my hair out! Hoping you can assist. In the following example, it appears that the first loop cannot get the correct size of the first array; yet using similar code for the second it works fine

$arrref   = $queryHandle->fetchall_arrayref();
$colnames = $queryHandle->{NAME};
print Dumper($colnames);
print Dumper($arrref);

print "A size:" . @colnames . "\n";
for ($i=0; $i < @colnames; $i++) {

     print "A: " . $i . " : " . $colnames[$i] ."\n";
}

for ($i=0; $i<= @arrref; $i++) {
      print "B size:" . @{$arrref->[$i]} . "\n";
    for ($j=0; $j< @{$arrref->[$i]}; $j++) {
        print "B: " . $i . " : " . $j . " : " . $arrref->[$i]->[$j] . 
+"\n";
    }    
}

C:\temp>perl 1.pl
$VAR1 = [
          'MEASURE',
          'CNT'
        ];
$VAR1 = [
          [
            '# PLTADM Queries (ex batch) ',
            '0'
          ]
        ];
A size:0
B size:2
B: 0 : 0 : # PLTADM Queries (ex batch)
B: 0 : 1 : 0

[toolic]

You should dereference your array refs:

use warnings;
#use strict;

$colnames = [
          'MEASURE',
          'CNT'
        ];
$arrref = [
          [
            '# PLTADM Queries (ex batch) ',
            '0'
          ]
        ];

my @colnames = @{ $colnames };
print "A size:" . @colnames . "\n";
for ($i=0; $i < @colnames; $i++) {

     print "A: " . $i . " : " . $colnames[$i] ."\n";
}

for ($i=0; $i<= @arrref; $i++) {
      print "B size:" . @{$arrref->[$i]} . "\n";
    for ($j=0; $j< @{$arrref->[$i]}; $j++) {
        print "B: " . $i . " : " . $j . " : " . $arrref->[$i]->[$j] . 
+"\n";
    }    
}

__END__

A size:2
A: 0 : MEASURE
A: 1 : CNT
B size:2
B: 0 : 0 : # PLTADM Queries (ex batch) 
B: 0 : 1 : 0

Tip #1 from the Basic debugging checklist: strict. See also:

• perldsc

[vinoth.ree]

Have you included

use strict;
use warnings;

There is no array with @colnames, so its printing 0, You have $colnames variable which has the array reference, you need to dereference it like

print "A size:" . @$colnames . "\n";

[Anonymous Monk]

It is because you're not using strict/warnings

Read this if you want to cut your development time in half!

$arrref and @arrref are two different variables, strict/warnings would have told you about it, Tutorials: Basic debugging checklist , brian's Guide to Solving Any Perl Problem

[jarrodb]

Thanks, Yes I normally do use strict, however I started this one from a very old copy of a script I did many years ago. I tend to only come back to perl every few years as needs arise so the dereferencing throws me off sometimes. (especially after midnight and a long day at work!) Thanks again; great quick replies greatly appreciated.