Quick Reference Guide to Array and Hash Manipulations

Array Manipulations

1. Do something to each item in an array:

foreach $item (@array) {

   # do something to $item;

}

2. Find the items in an array which match the condition:

@match = grep { $_ == 1 } @array;

Hash Manipulations

1. To initialize a hash

%food_color = (

                              “apple” => “red”,

                              “banana => “yellow”,

                              “lemon” => “yellow”,

                              “carrot” => “orange”

                        );

2. Print the hash keys

foreach $food (keys %food_color) {

   print “$food\n”;

}

3. Check if item is a hash key

foreach $name (“banana”, “martini”) {

   if (exists $food_color{$name}) {

      print “$name is a food.\n”;

   } else {

      print “$name is a drink.\n”;

   }

}

4. Do something with each key and value in a hash

while (($food, $color) = each(%food_color)) {

      print “$food is $color.\n”;

}

Alternatively

foreach $food (sort keys %food_color) {

      print “$food is $food_color{$food}.\n”;

}

5. Find the items in a hash which match the condition:

@match = grep { $hash{$_} == 1 } keys %hash;