Why is this array only printing the last number? - perl

Question

My first time working with Perl. I'm using it to take data from multiple cells from one Excel file and put them in another, existing Excel file.
I've managed to extract the data I need from the first file and put it into an #array. I started a new file to experiment with writing the data into the specific cells I need.
The problem is that when the script runs it has the same number in all cells, 18365. While the #rows arrays is working correctly and putting the number in the correct cell, the #revenue array only prints the last number.
Is there something I am overlooking or not understanding? Is there a better way to do this? I thank you in advance.
use warnings;
use strict;
use Spreadsheet::ParseExcel;
use Spreadsheet::ParseExcel::SaveParser;
my $parser = Spreadsheet::ParseExcel::SaveParser->new();
my $workbook = $parser->Parse('xls_test.xls');
if (!defined $workbook ) {
die $parser->error(), ".\n";
}
my $worksheet = $workbook->worksheet(0);
my #rows = (2, 10, 17);
my #revenue = (10200, 9025, 18365);
my $col = 2;
foreach my $rev (#revenue) {
foreach my $r (#rows) {
$worksheet->AddCell( $r, $col, "$rev" );
}
}
$workbook->SaveAs('xls_test.xls');

Answer 1

If you take your loop:
foreach my $rev (#revenue) {
foreach my $r (#rows) {
$worksheet->AddCell( $r, $col, "$rev" );
}
}
The last $rev to write is 18365, and you will overwrite the previous values in all 3 rows.
What you can do is creating a row-to-revenue hash from both your lists and traverse it:
my #rows = (2, 10, 17);
my #revenue = (10200, 9025, 18365);
my $col = 2;
my %data;
for my $i (0 .. $#rows) {
$data{$rows[$i]} = $revenue[$i]; # row => revenue
}
foreach $row (keys %data) {
$worksheet->AddCell($row, $col, $data{$row});
}

Answer 2

Here's an illustration of what your code does. I replaced the AddCell with a simple say, which is like print with a newline at the end.
use strict;
use warnings 'all';
use feature 'say';
my #rows = (2, 10, 17);
my #revenue = (10200, 9025, 18365);
my $col = 2;
say "row\tcol\trev";
foreach my $rev (#revenue) {
foreach my $r (#rows) {
say join "\t", $r, $col, $rev;
}
}
And this is the output:
row col rev
2 2 10200
10 2 10200
17 2 10200
2 2 9025
10 2 9025
17 2 9025
2 2 18365
10 2 18365
17 2 18365
As you can see, it iterates through all the revenues, and then for each revenue it writes to rows 2, 10 and 17.
2 2 10200
10 2 10200
17 2 10200
And here it goes again.
2 2 9025
10 2 9025
17 2 9025
Since it's always in the same column (that's the 2), the values get overwritten. That's why only the last round of values are there.
I don't really know what you are expecting as the correct output, but since you have fixed rows, you might want to use three columns? You could increase the $col variable after you're done writing all rows for each $rev.
foreach my $rev (#revenue) {
foreach my $r (#rows) {
$worksheet->AddCell( $r, $col, $rev );
}
$col++;
}
Now the output of our little program above would be like this, and all values would be there.
row col rev
2 2 10200
10 2 10200
17 2 10200
2 3 9025
10 3 9025
17 3 9025
2 4 18365
10 4 18365
17 4 18365
Note that I removed the double-quotes "" around $rev. You don't need to quote variables like that.