ruby hash with default value

To create a Ruby hash with a default value, you can use the Hash.new method and pass a default value as an argument. Here are the steps to create a hash with a default value:

  1. Start by defining the default value that you want the hash to return when accessing a non-existent key. For example, if you want the default value to be 0, you can set it as default_value = 0.

  2. Create a new hash using the Hash.new method and pass the default value as an argument. For example, hash = Hash.new(default_value).

  3. You can also set the default value using a block. Instead of passing a default value as an argument to Hash.new, you can pass a block that will be executed whenever a non-existent key is accessed. The block should return the desired default value. For example, hash = Hash.new { |h, k| h[k] = [] } will create a hash with an empty array as the default value for non-existent keys.

  4. You can access the default value by using the square brackets notation ([]) with a key that doesn't exist in the hash. For example, hash[:non_existent_key] will return the default value you specified.

  5. If you want to change the default value for the hash, you can assign a new value to the default attribute of the hash. For example, hash.default = new_default_value.

By following these steps, you can create a Ruby hash with a default value and manipulate it as needed.