hash.pl

use v5.14;

my %couples = (
    Yehuda => 'Ninet',
    Yossi  => 'Jager',
    Bibi   => 'Sarah',
    Brad   => 'Jeffiner',
);

$couples{Brad} = 'Angelina';
$couples{Turji} = 'Oshri';

while ( my ($m, $f) = each %couples ) {
    say "$m is with $f";
}

my @keys = keys %couples;
foreach my $k (keys %couples) {
    say "$k is with $couples{$k}";
}

my @values = values %couples;
say "values = @values";

hello.pl

use v5.14;

#################
# For older versions:
#
# use strict;
# use warnings;
#

#########################
# Variables

# Use "my" to declare a new variable
my $x = 7;
my $y = 15;

$y = 9;

my $name    = "Ynon Perek";
my $website = "ynonperek.com";

my $z = $x + $y;
$y *= 15;

my $text = "$name website is $website";
my $t    = $name . $website;

#############################
# Flow Control
#

if ( 2 < 5 ) {
    say "Hello World";
}

for ( my $i=0; $i < 10; $i ++ ) {
    say "i = $i";
}

my $n = 10;
while ( $n > 0 ) {
    $n--;
}

#####################
# Input/Output
#

say "Welcome To Perl. Who are you ?";
chomp( my $me = <> );

say "-----> Welcome, $me  <-------";


while (my $line = <>) {
    chomp $line;
    say "You said: $line";
}

##############
# Other Tips
#
# Show help on command chomp
# perldoc -f chomp
#
# List all perl functions:
# perldoc perlfunc

my $rnd = rand(10);
my $int = int($rnd);
say "rand = $rnd; int = $int";

re_solutions.pl

use v5.14;
use warnings;

my $all_digits = qr{([0-9])};
my $all_caps   = qr{[A-Z]};
my $caps_sep   = qr{[A-Z]([^A-Z]+|$)};

while(<>) {
    my @all_digits = /$all_digits/g;
    say "1" if @all_digits >= 2;
    say "2" if @all_digits == 4;

    say "3" if /[A-Z]{5}/;

    my @all_caps = /$caps_sep/g;
    say "4" if @all_caps == 5;

    say "5" if /^w.*\d$/;

    my @words = split;
    say "6" if @words >= 3;


    my @long_words = grep /...../, @words;
    say "7" if @long_words >= 2;

    s/foo/bar/ for (@words);

    say "8";

    ###############
    my @l = qw/red blue green white yellow/;

    # l1 has: blue, green, white, yellow
    my @l1 = grep /..../, @l;

    # l2 has: blue, white
    my @l2 = grep /e$/, @l;

    my @n = (1, 2, 3, 5, 9, 12, 14);

    my @n1 = grep { $_ % 2 == 0 } @n;
}

regexps.pl

use v5.14;
use warnings;

my $text = "My name is Inigo Montoya, you killed my father";

my $email_re = qr{^([a-zA-Z0-9_\-\.]+)@((\[[0-9]{1,3}\.[0-9]{1,3}\.[0-9]{1,3}\.)|(([a-zA-Z0-9\-]+\.)+))([a-zA-Z]{2,4}|[0-9]{1,3})(\]?)$};

my $config_line_re = qr {
# title  = Ultimate Fighter 7
# author = Mad Mike
    (\w+)   \s*  =    \s*    (.+)
}x;


my $start_with_long_word_re = qr{

# a long word is longer than 4 lowercase
# letters
    ^       [a-z]{4,}

}x;

# Use =~ to match a regular expression
#
if ( $text =~ /[a-z]{4,}/ ) {
    say "Your text has a long word";
}

my $digits_re = qr{ ([0-9]) }x;

#while (<>) {
    #my ($k, $v) = /$config_line_re/;
    #next if ! defined($k);

    #say "title: $k, value: $v";
#}


#while (<>) {
    #my @digits = /$digits_re/;
    #say "@digits";
#}

while(<>) {
#   replace in a variable
#   $text =~ s/dog/cat/;

    s/dog/cat/;
    s/$spaces_at_start//;
    s/\s+$//;
    say;
}

(my $new = $old) =~ s/foo/bar;

my $new = $old;
$new =~ s/foo/bar;