Explore Perl Learn Perl Must-knows Functions that always return

Challenges

1. What is the longest word in the string 'If music be the food of love play on.'


$text = "If music be the food of love play on.";
@words = (split( /\s+/, $text)); 
@words_sort = sort ({length($a) <=> length($b)} @words);

print("Longest word: $words_sort[-1]\n");    
print("\n" . "-" x 35, "\n");

2. Find the intersection of two arrays with the numbers 1,2,3,4,5 and 3,4,5,6,7.


@array1 = (1, 2, 3, 4, 5);
@array2 = (3, 4, 5, 6, 7);

@intersection = grep { $elem = $_; grep { $elem == $_ } @array2 } @array1;

print "Intersection: @intersection\n";

A better solution can be found here > challenge 4

3. Given an array with positive integers. How many are even?


print( scalar( grep { !($_ % 2) } qw( 1 2 3 4 5 ) ) . "\n" );

4. Pass this list ab, abc, abcd, abcde, abcdef, abcdefg, abcdefgh as an anonymous array to a function that determines how many items have an even number of characters.


sub count_even_words {
    scalar( grep { !(length($_) % 2) } @{$_[0]} );
}

print("Number of even character items: " . count_even_words([qw(ab abc abcd abcde abcdef abcdefg abcdefgh)]) . "\n");

5. Pass this list 12, 123, 1234, 12345, 123456, 1234567, 12345678 as an anonymous array to a function that determines how many items have an even number of digits.


sub count_even_digits {
    scalar( grep { !(split('',$_) % 2) } @{$_[0]} );
}

print("Number of even digits: " . count_even_digits([qw(12, 123, 1234, 12345, 123456, 1234567, 12345678)]) . "\n");

6. Given a hash where keys and values are numbers. Find all keys where key or value > 50


%mc_hash = (
100 => 10,
50 => 40,
10 => 60,
200 => 70 );

@mc_sel = grep { $_ > 50 or $mc_hash{$_} > 50 } keys %mc_hash;
print("@mc_sel\n");

7. Rolling a 6-sided dice 20 times results in the following data: 5 1 2 1 3 3 1 4 3 1 2 1 3 4 4 5 6 2 3 1. Print a frequency table where the frequency of each number is represented by an asterisk.


$sides_dice = 6;
@array = qw(5 1 2 1 3 3 1 4 3 1 2 1 3 4 4 5 6 2 3 1);
@freq = ();

for ($i = 1; $i <= $sides_dice; $i++) {
  push( @freq, scalar( grep { $_ == $i } @array) );
  print($i . " | " . ("*" x $freq[$i - 1]) . "\n");  
}

8. Rewrite @list = ( grep { $_ < 10 } qw( 1 2 3 5 8 13 21 34) ); using foreach and push


@list = ();
foreach ( qw( 1 2 3 5 8 13 21 34) ) {
    push ( @list, $_ ) if ($_ < 10);
}