how to display the hash value from my sample data - perl

Question

I'm learning perl at the moment, i wanted to ask help to answer this exercise.
My objective is to display the hash value of PartID 1,2,3
the sample output is displaying lot, wafer, program, version, testnames, testnumbers, hilimit, lolimit and partid values only.
sample data
lot=lot123
wafer=1
program=prgtest
version=1
Testnames,T1,T2,T3
Testnumbers,1,2,3
Hilimit,5,6,7
Lolimit,1,2,3
PartID,,,,
1,3,0,5
2,4,3,2
3,5,6,3
This is my code:
#!/usr/bin/perl
use strict;
use Getopt::Long;
my $file = "";
GetOptions ("infile=s" => \$file ) or die("Error in command line arguments\n");
my $lotid = "";
open(DATA, $file) or die "Couldn't open file $file";
while(my $line = <DATA>) {
#print "$line";
if ( $line =~ /^lot=/ ) {
#print "$line \n";
my ($dump, $lotid) = split /=/, $line;
print "$lotid\n";
}
elsif ($line =~ /^program=/ ) {
my ($dump, $progid) = split /=/, $line;
print "$progid \n";
}
elsif ($line =~ /^wafer=/ ) {
my ($dump, $waferid) = split /=/, $line;
print "$waferid \n";
}
elsif ($line =~ /^version=/ ) {
my ($dump, $verid) = split /=/, $line;
print "$verid \n";
}
elsif ($line =~ /^testnames/i) {
my ($dump, #arr) = split /\,/, $line;
foreach my $e (#arr) {
print $e, "\n";
}
}
elsif ($line =~ /^testnumbers/i) {
my ($dump, #arr1) = split /\,/, $line;
foreach my $e1 (#arr1) {
print $e1, "\n";
}
}
elsif ($line =~ /^hilimit/i) {
my ($dump, #arr2) = split /\,/, $line;
foreach my $e2 (#arr2) {
print $e2, "\n";
}
}
elsif ($line =~ /^lolimit/i) {
my ($dump, #arr3) = split /\,/, $line;
foreach my $e3 (#arr3) {
print $e3, "\n";
}
}
}
Kindly help add to my code to display Partid 1,2,3 hash.

Answer 1

So I've rewritten your code a little to use a few more modern Perl idioms (along with some comments to explain what I've done). The bit I've added is near the bottom.
#!/usr/bin/perl
use strict;
# Added 'warnings' which you should always use
use warnings;
# Use say() instead of print()
use feature 'say';
use Getopt::Long;
my $file = "";
GetOptions ("infile=s" => \$file)
or die ("Error in command line arguments\n");
# Use a lexical variable for a filehandle.
# Use the (safer) 3-argument version of open().
# Add $! to the error message.
open(my $fh, '<', $file) or die "Couldn't open file $file: $!";
# Read each record into $_ - which makes the following code simpler
while (<$fh>) {
# Match on $_
if ( /^lot=/ ) {
# Use "undef" instead of a $dump variable.
# split() works on $_ by default.
my (undef, $lotid) = split /=/;
# Use say() instead of print() - less punctuation :-)
say $lotid;
}
elsif ( /^program=/ ) {
my (undef, $progid) = split /=/;
say $progid;
}
elsif ( /^wafer=/ ) {
my (undef, $waferid) = split /=/;
say $waferid;
}
elsif ( /^version=/ ) {
my (undef, $verid) = split /=/;
say $verid;
}
elsif ( /^testnames/i) {
my (undef, #arr) = split /\,/;
# Changed all of these similar pieces of code
# to use the same variable names. As they are
# defined in different code blocks, they are
# completely separate variables.
foreach my $e (#arr) {
say $e;
}
}
elsif ( /^testnumbers/i) {
my (undef, #arr) = split /\,/;
foreach my $e (#arr) {
say $e;
}
}
elsif ( /^hilimit/i) {
my (undef, #arr) = split /\,/;
foreach my $e (#arr) {
say $e;
}
}
elsif ( /^lolimit/i) {
my (undef, #arr) = split /\,/;
foreach my $e (#arr) {
say $e;
}
}
# And here's the new bit.
# If we're on the "partid" line, then read the next
# three lines, split each one and print the first
# element from the list returned by split().
elsif ( /^partid/i) {
say +(split /,/, <$fh>)[0] for 1 .. 3;
}
}
Update: By the way, there are no hashes anywhere in this code :-)
Update 2: I've just realised that you only have three different ways to process the data. So you can simplify your code drastically by using slightly more complex regexes.
#!/usr/bin/perl
use strict;
use warnings;
use feature 'say';
use Getopt::Long;
my $file = "";
GetOptions ("infile=s" => \$file)
or die ("Error in command line arguments\n");
open(my $fh, '<', $file) or die "Couldn't open file $file: $!";
while (<$fh>) {
# Single value - just print it.
if ( /^(?:lot|program|wafer|version)=/ ) {
my (undef, $value) = split /=/;
say $value;
}
# List of values - split and print.
elsif ( /^(?:testnames|testnumbers|hilimit|lolimit)/i) {
my (undef, #arr) = split /\,/;
foreach my $e (#arr) {
say $e;
}
}
# Extract values from following lines.
elsif ( /^partid/i) {
say +(split /,/, <$fh>)[0] for 1 .. 3;
}
}