hashes in perl

In Perl, a hash is a variable that can hold an unordered collection of key-value pairs, similar to a dictionary in Python or an associative array in other programming languages. Hashes are denoted by the % sigil, and can be declared using the my keyword. Here's an example:

my %ages = ("Alice" => 25, "Bob" => 30, "Charlie" => 35); # declare a hash of names and ages

Hash keys and values can be of any scalar type, including strings, numbers, and references. To access individual values in a hash, you can use the key as an index in curly braces ($hash{key}). For example:

my %ages = ("Alice" => 25, "Bob" => 30, "Charlie" => 35);
print $ages{"Alice"}; # prints 25
print $ages{"Charlie"}; # prints 35

You can also modify individual values in a hash by assigning a new value to the corresponding key:

my %ages = ("Alice" => 25, "Bob" => 30, "Charlie" => 35);
$ages{"Alice"} = 26;
print %ages; # prints "Alice" => 26, "Bob" => 30, "Charlie" => 35

In addition to accessing individual values in a hash, you can also loop over all the keys and values using the keys and values functions. For example:

my %ages = ("Alice" => 25, "Bob" => 30, "Charlie" => 35);
foreach my $name (keys %ages) {
  my $age = $ages{$name};
  print "$name is $age years old\n";
}

In summary, hashes in Perl are used to hold an unordered collection