hash.rb

# Hash
# A hash in Ruby is a collection of key-value pairs. 
# Each key is unique and maps to a value. You can create a hash by enclosing key-value pairs in curly braces (`{}`) or by using the `Hash.new` constructor.

person = {
  name: "Luthfi",
  age: 25,
  is_married: false,
  live: {
    city: "Jakarta",
    country: "Indonesia"
  }
}

puts person.inspect  # Output: {:name=>"Luthfi", :age=>25, :is_married=>false, :live=>{:city=>"Jakarta", :country=>"Indonesia"}}

# Accessing values
puts person[:name]  # Output: Luthfi
puts person[:age]   # Output: 25
puts person[:live][:city]  # Output: Jakarta

# Modifying values
person[:age] = 26
puts person[:age]  # Output: 26

# Adding key-value pairs
person[:hobby] = "coding"
puts person.inspect  # Output: {:name=>"Luthfi", :age=>26, :is_married=>false, :live=>{:city=>"Jakarta", :country=>"Indonesia"}, :hobby=>"coding"}

# Removing key-value pairs
person.delete(:is_married)
puts person.inspect  # Output: {:name=>"Luthfi", :age=>26, :live=>{:city=>"Jakarta", :country=>"Indonesia"}, :hobby=>"coding"}

# Hash methods
puts person.keys.inspect  # Output: [:name, :age, :live, :hobby] (Returns an array of all keys in the hash)
puts person.values.inspect  # Output: ["Luthfi", 26, {:city=>"Jakarta", :country=>"Indonesia"}, "coding"] (Returns an array of all values in the hash)
puts person.has_key?(:name)  # Output: true (Checks if the key :name exists in the hash)
puts person.has_value?("Luthfi")  # Output: true (Checks if the value "Luthfi" exists in the hash)


# Hashes can also be nested, allowing you to create complex data structures. You can access nested values using multiple keys.
puts person.dig(:live, :country)  # Output: Indonesia (Accessing the value of :country within the nested :live hash)

# delete method is used to remove a key-value pair from a hash by specifying the key. It returns the value associated with the removed key, or nil if the key was not found.
removed_value = person.delete(:hobby)  # Removes the key :hobby and returns its value
puts removed_value  # Output: coding (The value that was removed)
puts person.inspect  # Output: {:name=>"Luthfi", :age=>26, :live=>{:city=>"Jakarta", :country=>"Indonesia"}} (The hash after the key-value pair has been removed)

# delete all hash elements
person.clear  # This will remove all key-value pairs from the hash, leaving it empty.
puts person.inspect  # Output: {} (The hash is now empty)